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CHEMISTRY 


IN  ITS  APPLICATION  TO 


AGRICULTUEE  AND  PHYSIOLOGY. 

BY  I 

JUSTUS  LIEBIG,  M.D.,  Ph.D.,  F.R.S.,  M.R.I.A., 

If 

PROFESSOR  OF  CHEMISTRY  IN  THE  UNIVERSITT  OF  6IESSEN, 
ETC.,  ETC.,  ETC. 

'  / 

EDITED  FROM  THE  MANUSCRIPT  OF  THE  AUTHOR 

By  LYON  PLAYFAIR,  Ph.D. 

VERY  NUMEROUS  ADDITIONS,  AND   A  NEW  CHAPTER  ON  SOILS. 


THIRD  AMERICAN,  FROM  THE  SECOND  ENGLISH  EDITION, 

WITH 
NOTES,  AND  APPENDIX, 

BY 

JOHN  W.  WEBSTER,  M.D., 

ERVINO  PROFESSOR  OF  CHEMISTRY  IN  HARVARD  UNIVERSITY. 

iFOB*'      CAMBRIDGE: 
PUBLISHED  BY  JOHN  OWEN. 

BOSTON,  JAMES   MUNROB  AND  COMPANY,  AND   CHARLES  C.  LITTLE  AND  JAMES  BROWN  ; 

NEW  YORK,  WILEY  AND  PUTNAM,  AND  GEOROK  C.  THORBURN  ;   PHILADELPHIA, 

THOMAS,  COWPERTHWAIT,  AND  COMPANY,  AND  CAREY  AND  HART ; 

BALTIMORE,    CUSHINO  AND   BROTHER. 

1842. 


'«» 


y 


V) 
V 


■■') 


Entered  according  to  Act  of  Congress,  in  the  year  1842,  by 

John  Owen, 

in  the  Clerk's  office  erf*  the  District  Court  of  the  District  of  Massachusetts. 


CAMBRIDGE; 

STEREOTYPED   AND   PRINTED   BY 

METCALF,   KEITH,    AND    NICHOLS, 

PRINTERS  TO  THE  UNIVERSITY. 


CONTENTS. 


Preface  to  the  Third  American  Edition 

Dedication 

Preface  to  the  Second  English  Edition 

Object  of  the  Work 


PAGB 

V 

XIII 

XVII 

21 


PART  FIRST. 

ON  THE  CHEMICAL  PROCESSES  IN  THE  NUTRITION  OF  VEGETABLES. 

dRAPTEB  PAGE 

I.  —  On  the  Constituent  Elements  of  Plants    .  .  24 

n.  —  On  the  Assimilation  of  Carbon  .  .  .30 

ni.  — On  the  Origin  and  Action  of  Humus        .  .  63 

IV.  —  On  the  Assimilation  of  Hydrogen      .  .  .80 

V.  —  On  the  Origin  and  Assimilation  of  Nitrogen        .  65 

VI.  —  On  the  Inorganic  Constituents  of  Plants       ,  .     105 

Vn.  — The  Art  of  Culture         ....  126 

Vin. — On  the  Alternation  (Rotation)  of  Crops        .  .161 

IX.  —  On  Manure  .....  174 

Supplementary  Chapter. —On  the  Chemical  Constitu- 
ents of  Soils  .  .  .  .  .  208 

Appendix  to  Part  I.  .....     249 

Action  of  Charcoal  on  Vegetation  ,  •  249 

Mode  of  Manuring  Vines         ....     253 

Root  Secretions      .  .  ,  ,  •  ^56 

Peat  Compost  .  .  •  •  .     258 

Source  of  the  Carbon  of  Plants     .  .  .  260 

Source  of  the  Hydrogen  of  Plants      .  .  .     263 

Dependence  of  the  Nutritive  Qualities  of  Plants  on 

Nitrogen  .  .  .  .  .265 


iv  CONTENTS. 

Difference  in  the  Power  of  Plants  to  decompose 

Ammonia  .....  266 

Practical  Inferences  .  .  •  .  268 

Use  of  Phosphate  of  Soda      ....  286 

Daniell's  Artificial  Manure  .  •  •  287 


PART  SECOND. 

ON  THE  CHEMICAL  PROCESSES  OF  FERMENTATION,  DECAY,  AND 

PUTREFACTION. 

CHAPTER  PAGE 

I.  —  Chemical  Transformations            .            .            .  289 
n.  —  On  the  Causes  which  effect  Fermentation,  Decay, 

and  Putrefaction         .     .             .             .             .  292 
ni. — Fermentation  and  Putrefaction          .            .            .  300 
IV.  —  On  the  Transformation  of  Bodies  which  do  not  con- 
tain Nitrogen  as  a  constituent,  and  of  those  in 
which  it  is  present       ....  305 
V. — Fermentation  of  Sugar         .             ,            .            .313 
VI. — Eremacausis,  or  Decay                .            .            .  322 
Vn.  — Eremacausis  of  Bodies  destitute  of  Nitrogen :  For- 
mation of  Acetic  Acid             .            .            .  329 
VTEI.  —  Eremacausis  of  Substances  containing  Nitrogen  : 

Nitrification                 ....  334 

IX.  — On  Vinous  Fermentation  :  Wine  and  Beer               .  338 

X.  -—On  the  Decay  of  Woody  Fibre                .            .  357 

XI.  — On  Vegetable  Mould  .  .  .  .363 

Xn.  —  On  the  Mouldering  of  Bodies :  Paper,  Brown  Coal, 

and  Mineral  Coal              .            .            .            .  365 

Xni. — On  Poisons,  Contagions,  and  Miasms                .  373 
Appendix  to  Part  II.           .            .            ,            .            .415 


Tables,  —  Showing  the  Proportion  between  the  Hessian 

and  English  Standard  of  Weights  and  Measures      416 
Index  .  .  ,  .  .  .  419 


PREFACE 


TO   THE 


THIRD   AMERICAN  EDITION. 


This  volume  constitutes  the  First  Part  of  Professor 
Liebig's  Report  on  Organic  Chemistry,  drawn  up  by 
request  of  the  British  Association  for  the  Advancement 
of  Science.* 

The  interest  excited  in  Great  Britain  on  the  appear- 
ance of  this  work  from  one  of  the  most  eminent 
chemists  in  Europe,  and  the  high  encomiums  be- 
stowed upon  it  by  individuals,  and  leEirned  bodies, 
together  with  the  various  notices  of  it  which  have 
been  published  by  Professor  Lindley,  Professor  Dau- 
beny,  and  others,  all  concurring  in  the  opinion,  that 
the  information  it  contains  is  of  great  amount,  and 
that  from  its  publication  might  be  dated  a  new  era 

*  The  Second  Part  has  just  been  published,  viz.,  "Animal  Chemistry, 
or  Organic  Chemistry  in  its  Application  to  Physiology  and  Pathology. 
By  Justus  Liebig,  M.  D.,  F.  R.  S.,  M.  R.  1.  A.,  Professor  of  Chemistry 
in  the  University  of  Giessen,  &c.,  &c.,  &c.  Edited  from  the  Author's 
Manuscript,  by  William  Gregory,  M.  D.,  F.  R.  S.,  M.  R.  I.  A., 
Professor  of  Medicine  and  Chemistry  in  the  University  and  King's 
College,  Aberdeen.  With  Additions,  Notes,  and  Corrections,  by  Dr. 
Gregory,  and  others  by  John  W.  Webster,  M.  D.,  Erving  Professor  of 
Chemistry  in  Hirvard  University." 

a* 


Vi  PREFACE  TO  THE 

in  the  art  of  agriculture,  induced  the  editor  to  suggest 
its  republication  in  this  country. 

Contrary  to  the  expectations  of  the  author,  and  of 
the  editor,  the  work  has  received  the  attention  not 
only  of  scientific  readers,  for  whom  it  was  written, 
but  of  practical  agriculturists,  and4those  who  could 
hardly  have  been  supposed  prepared  to  derive  much 
advantage  from  its  perusal.  The  influence  of  the 
opinions  of  Professor  Liebig,  and  the  impetus  the 
appearance  of  the  present  work  gave  to  the  advance- 
ment of  scientific  agriculture,  have  been  evinced  by  the 
many  publications  which  have  since  appeared,  both  in 
Great  Britain  and  in  this  country. 

What  is  valuable  in  too  many  of  these  publications, 
diluted  as  it  has  been  and  mingled  with  erroneous 
statements,  was  for  the  first  time  given  in  a  consistent 
shape  in  the  present  work. 

Although  the  fact  that  nitrogen  is  essential  to  the 
nutrition  of  plants  was  known  before  the  publication 
of  Professor  Liebig's  work,  and  it  had,  indeed,  been 
ascertained  by  Saussure,  that  germinating  seeds  absorb 
nitrogen,  it  was  not  supposed  that  it  is  derived  from 
the  atmosphere  exclusively.  And  this  has  been 
deemed  the  chief  discovery  of  the  author,  so  far  as 
practical  questions  are  concerned.  It  had  indeed  been 
suspected,  that  very  small  quantities  of  ammonia  in 
the  atmosphere  might  furnish  the  nitrogen,  ammonia 
being  a  compound  of  nitrogen  and  hydrogen.  It 
may  be  objected,  that  the  quantity  of  ammonia  pres- 
ent in  the  atmosphere,  and  in  rain  and  snow  water,  is 


THIRD  AMERICAN  EDITION.  vii 

exceedingly  small,  quite  insufficient  for  the  supply  of 
all  the  nitrogen  that  enters  into  the  vegetable  struc- 
ture. To  this  it  has  been  replied  by  Professor  Lind- 
ley,  in  an  elaborate  review  of  Liebig's  work,  that 
^^  the  quantity  of  ammonia  given  off  from  thousands 
of  millions  of  putrefying  animals  must  furnish  an 
abundant,  an  everlasting  source  of  that  principle." 

Important  as  ammonia,  or  its  nitrogen,  is  conceived 
to  be  to  plants,  it  will  be  seen  that  Liebig  considers 
carbon  not  less  so. 

Since  the  appearance  of  the  former  editions  of  this 
work,  the  opinions  of  American  chemists  in  regard  to 
humus,  have  become  so  generally  diffused,  in  the 
various  Agricultural  Reports,  that  it  has  not  been 
deemed  necessary  to  retain,  in  this  edition,  much  that 
was  appended  to  the  second. 

Professor  Lindley,  in  speaking  of  humus,  recogni- 
ses it  as  "  the  dark  substance  which  remains  when 
manure  is  thoroughly  rotted,  and  which  colors  the 
soil  black,  and  without  going  into  any  technical  ex- 
amination of  this  product,  we  may  state,"  he  con- 
tinues, "that  it  is  a  substance  formed  by  the  decay  of 
plants,  and  very  rich  in  carbon."  He  then  quotes  the 
expression  of  Liebig,  that  this  substance,  in  the  form 
in  which  it  exists  in  the  soil,  does  not  yield?  nourish- 
ment to  plants,  and  expresses  surprise,  that  the  author  ^ 
should  have  thought  it  worth  his  while  to  raise  such 
a  phantom  for  the  mere  pleasure  of  subduing  it.  for 
no  one  in  Great  Britain  now  entertains  the  opinion, 
that  humus  is  in  itself  the  food  of  plants.     ^^  Every 


Vlll  ^  PREFACE  TO  THE 

Student  of  botany  is  taught,  that  humus  becomes  the 
food  of  plants  only  by  combining  with  the  oxygen  of " 
the  atmosphere  and  forming  carbonic  acid  gas,  and 
hence  the  great  importance  of  preserving  the  roots  of 
plants  in  communication  with  the  atmosphere,  which 
is  the  great  source  of  oxygen." . 

In  noticing  the  effect  of  alkalies,  Professor  Lindley 
remarks,  that  it  will  lead  to  the  explanation  of  many 
things  that  were  inexplicable  before.  "  When  it  is 
said,  that  a  plant  becomes  tired  of  a  soil,  and  we  find 
that  manuring  fails  to  invigorate  it,  the  destruction  of 
alkalies  in  the  soil,  and  the  want  of  a  sufficient  supply 
of  those  bases  in  the  manure,  seem  to  offer  a  solution 
of  the  enigma.  And  in  like  manner  the  gradual  de- 
cay of  trees  in  public  squares  and  promenades,  where 
the  soil  is  incessantly  robbed  of  alkaline  matter  for 
the  sake  of  neatness,  may  probably  be  ascribed  to  the 
same  cause.  So  also  the  injurious  action  of  weeds  is 
explained,  by  their  robbing  the  soil  of  that  particular 
kind  of  food  which  is  necessary  to  the  crops  among 
which  they  grow.  Each  will  partake  of  the  compo- 
nent parts  of  the  soil,  and  in  proportion  to  the  vigor 
of  their  growth,  that  of  the  crop  must  decrease ;  for 
what  one  receives  the  others  are  deprived  of." 

"It  is  impossible  for  any  one  acquainted  with  gar- 
^  dening  not  to  perceive  the  immense  importance  of 
these  considerations,  which  show,  that  by  adopting 
the  modern  notion,  that  the  action  of  soil  is  chiefly 
mechanical,  the  science  of  horticulture  has  been  car- 
ried backwards,  instead  of  being  advanced ;  and  that 


THIRD  AMERICAN  EDITION.  ix 

the  most  careful  examination  of  the  chemical  nature 
both  of  the  soil  in  which  a  given  plant  grows,  and  of 
the  plant  itself,  must  be  the  foundation  of  all  exact 
and  economical  methods  of  cultivation.'' 

Of  the  importance  of  alkalies  and  salts  to  plants, 
there  would  seem  to  be  no  doubt,  and  although  the 
credit  of  this  discovery  is  in  England  given  to  Liebig, 
it  was  not  new  in  the  United  States,  having  been  an- 
nounced by  Dr.  S.  L.  Dana  of  Lowell,  and  urged 
upon  the  attention  of  cultivators  in  the  various  Re- 
ports on  the  Agriculture  of  Massachusetts,  several 
years  ago. 

As  in  this  work  many  chemical  and  technical  terms 
are  necessarily  made  use  of,  and  it  may  come  into  the 
hands  of  some  persons  who  are  not  familiar  with  them, 
explanatory  notes  have  been  added  which  it  is  hoped 
may  render  the  text  more  intelligible.  The  notes 
that  are  contained  in  the  original  work  are  distin- 
guished by  initials  or  abbreviations. 

A  valuable  addition  has  been  made  in  the  extracts 
from  the  lectures  delivered  after  the  appearance  of 
Liebig's  work  by  Professor  Daubeny  at  Oxford,  on 
Agriculture  and  Rural  Economy.  The  greater  part 
of  the  third  lecture  is  given  in  the  Appendix,  being 
a  summary  of  the  practical  applications  of  the  prin- 
ciples developed  and  discussed  in  the  body  of  this 
work. 

It  has  been  highly  gratifying  to  the  editor,  to  learn 
from  the  gentleman  under  whose  supervision  the  work 
first  appeared  in  England,  that  its  republication,  and 


X  PREFACE  TO  THE 

the  manner  in  which  it  has  been  edited  in  this  coun- 
try, have  met  with  his  entire  approbation.  To  Dr. 
Playfair  the  editor  is  also  indebted  for  some  valuable 
suggestions  which  were  followed  in  preparing  the 
second  edition,  and  for  which  he  would  express  his 
thanks. 

A  copious  index,  in  which  the  original  work  is  de- 
ficient, has  been  added,  and  numerous  errors  of  the 
English  press  have  been  corrected. 

The  estimation  in  which  Professor  Liebig's  work 
was  viewed  by  the  ''British  Association  for  the  Ad- 
vancement of  Science,"  before  whom  it  was  brought 
as  a  Report,  has  been  expressed  by  Professor  Gregory, 
of  King's  College,  in  the  remark,  "  that  the  Association 
had  just  reason  to  be  proud  of  such  a  work,  as  origi- 
nating in  their  recommendation." 

On  the  30th  of  November,  1840,  at  the  anniversary 
meeting  of  the  Royal  Society,  one  of  the  Copley 
medals  was  awarded  to  the  author ;  and  on  this  occa- 
sion, in  his  absence,  the  President,  the  Marquis  of 
Northampton,  addressed  his  representative,  Professor 
Daniell,  as  follows. 

"  Professor  Daniell,  I  hold  in  my  hand,  and  deliver 
to  you  one  of  the  Copley  medals,  which  has  been 
awarded  by  us  to  Professor  Liefeig.  My  principal 
difficulty,  in  the  present  exercise  of  this  the  most 
agreeable  part  of  my  official  duty,  is  to  know  wheth- 
er to  consider  M.  Liebig's  inquiries  as  most  important 
in  a  chemical  or  in  a  physiological  light.  However 
that  may  be,  he  has  a  double  claim  on  the  scientific 


THIRD  AMERICAN  EDITION.  XI 

world,  enhanced  by  the  practical  and  useful  ends  to 
which  he  has  turned  his  discoveries." 

To  Dr.  S.  L.  Dana,  of  Lowell,  the  editor  would  ac- 
knowledge his  obligations  for  valuable  suggestions 
and  the  communication  of  some  important  additions, 
and  also  to  Mr.  Charles  E.Buckingham,  of  the  Medical 
School  of  this  University,  for  his  valuable  assistance 
in  correcting  the  proofs. 

J.  W.  W. 

Cambridge,  September,  1842. 


TO 


THE  BRITISH  ASSOCIATION 


FOR   THE 


ADVANCEMENT  OF  SCIENCE. 


One  of  the  most  remarkable  features  of  modern 
times  is  the  combination  of  large  numbers  of  indi- 
viduals representing  the  whole  intelligence  of  nations, 
for  the  express  purpose  of  advancing  science  by  their 
united  efforts,  of  learning  its  progress,  and  of  commu- 
nicating new  discoveries.  The  formation  of  such  as- 
sociations is,  in  itself,  an  evidence  that  they  were 
needed. 

It  is  not  every  one  who  is  called  by  his  situation 
in  life  to  assist  in  extending  the  bounds  of  science ; 
but  all  mankind  have  a  claim  to  the  blessings  and 
benefits  which  accrue  from  its  earnest  cultivation. 
The  foundation  of  scientific  institutions  is  an  ac- 
knowledgment of  these  benefits,  and  this  acknowl- 
edgment,  proceeding  from  whole  nations,  may  be 
considered  as  the  triumph  of  mind  over  empiricism. 

Innumerable  are  the  aids  afforded  to  the  means  of 
life,  to  manufactures  and  to  commerce,  by  the  truths 

b 


TO 


THE  BRITISH  ASSOCIATION 


FOR   THE 


ADVANCEMENT  OF  SCIENCE. 


One  of  the  most  remarkable  features  of  modern 
times  is  the  combination  of  large  numbers  of  indi- 
viduals representing  the  whole  intelligence  of  nations, 
for  the  express  purpose  of  advancing  science  by  their 
united  efforts,  of  learning  its  progress,  and  of  commu- 
nicating new  discoveries.  The  formation  of  such  as- 
sociations is,  in  itself,  an  evidence  that  they  were 
needed. 

It  is  not  every  one  who  is  called  by  his  situation 
in  life  to  assist  in  extending  the  bounds  of  science; 
but  all  mankind  have  a  claim  to  the  blessings  and 
benefits  which  accrue  from  its  earnest  cultivation. 
The  foundation  of  scientific  institutions  is  an  ac- 
knowledgment of  these  benefits,  and  this  acknowl- 
edgment, proceeding  from  whole  nations,  may  be 
considered  as  the  triumph  of  mind  over  empiricism. 

Innumerable  are  the  aids  afforded  to  the  means  of 
life,  to  manufactures  and  to  commerce,  by  the  truths. 

h 


XIV  DEDICATION. 

which  assiduous  and  active  inquirers  have  discovered 
and  rendered  capable  of  practical  application.  But  it 
is  not  the  mere  practical  utility  of  these  truths  which 
is  of  importance.  Their  influence  upon  mental  cul- 
ture is  most  beneficial ;  and  the  new  views  acquired 
by  the  knowledge  of  them  enable  the  mind  to  recog- 
nise, in  the  phenomena  of  nature,  proofs  of  an  Infinite 
Wisdom,  for  the  unfathomable  profundity  of  which, 
language  has  no  expression. 

At  one  of  the  meetings  of  the  chemical  section  of 
the  "  British  Association  for  the  Advancement  of 
Science,"  the  honorable  task  of  preparing  a  Report 
upon  the  state  of  Organic  Chemistry  was  imposed 
upon  me.  In  the  present  work  I  present  to  the  As- 
sociation a  part  of  this  Report. 

I  have  endeavored  to  develop,  in  a  manner  corre- 
spondent to  the  present  state  of  science,  the  fundamen- 
tal principles  of  Chemistry  in  general,  and  the  laws 
of  Organic  Chemistry  in  particular,  in  their  applica- 
tions to  Agriculture  and  Physiology ;  to  the  causes  of 
fermentation,  decay,  and  putrefaction  ;  to  the  vinous 
and  acetous  fermentations,  and  to  nitrification.  The 
conversion  of  woody  fibre  into  wood  and  mineral  coal, 
the  nature  of  poisons,  contagions,  and  miasms,  and 
the  causes  of  their  action  on  the  living  organism,  have 
been  elucidated  in  their  chemical  relations. 

I  shall  be  happy  if  I  succeed  in  attracting  the  at- 
tention of  men  of  science  to  subjects  which  so  well 
merit  to  engage  their  talents  and  energies.  Perfect 
Agriculture  is  the  true  foundation  of  all  trade  and  in- 


DEDICATION.  XV 

dustry,  —  it  is  the  foundation  of  the  riches  of  states. 
But  a  rational  system  of  Agriculture  cannot  be  formed 
without  the  application  of  scientific  principles ;  for 
such  a  system  must  be  based  on  an  exact  acquaintance 
with  the  means  of  nutrition  of  vegetables,  and  with 
the  influence  of  soils  and  action  of  manure  upon  them. 
This  knowledge  we  must  seek  from  chemistry,  which 
teaches  the  mode  of  investigating  the  composition  and 
of  studying  the  characters  of  the  difierent  substances 
from  which  plants  derive. their  nourishment. 

The  chemical  forces  play  a  part  in  all  the  processes 
of  the  living  animal  organism  ;  and  a  number  of  trans- 
formations and  changes  in  the  living  body  are  exclu- 
sively dependent  on  their  influence.  The  diseases  in- 
cident to  the  period  of  growth  of  man,  contagion  and 
contagious  matters,  have  their  analogues  in  many 
chemical  processes.  The  investigation  of  the  chemi- 
cal connexion  subsisting  between  those  actions  pro- 
ceeding in  the  living  body,  and  the  transformations 
presented  by  chemical  compounds,  has  also  been  a 
subject  of  my  inquiries.  A  perfect  exhaustion  of  this 
subject,  so  highly  important  to  medicine,  cannot  be 
expected  without  the  cooperation  of  physiologists. 
Hence  I  have  merely  brought  forward  the  purely 
chemical  part  of  the  inquiry,  and  hope  to  attract  at- 
tention to  the  subject. 

Since  the  time  of  the  immortal  author  of  the  "  Ag- 
ricultural Chemistry,"  no  chemist  has  occupied  him- 
self in  studying  the  applications  of  chemical  principles 
to  the  growth  of  vegetables,  and  to  organic  processes. 


XVI  DEDICATION. 

I  have  endeavored  to  follow  the  path  marked  out  by 
Sir  Humphry  Davy,  who  based  his  conclusions  only 
on  that  which  was  capable  of  inquiry  and  proof. 
This  is  the  path  of  true  philosophical  inquiry,  which 
promises  to  lead  us  to  truth,  —  the  proper  object  of 
our  research. 

In  presenting  this  Report  to  the  British  Association 
I  feel  myself  bound  to  convey  my  sincere  thanks  to 
Dr.  Lyon  Playfair,  of  St.  Andrew's,  for  the  active  as- 
sistance which  has  been  afforded  me  in  its  preparation 
by  that  intelligent  young  chemist  during  his  residence 
in  Giessen.  I  cannot  suppress  the  wish,  that  he  may 
succeed  in  being  as  useful,  by  his  profound  and  well- 
grounded   knowledge   of    chemistry,   as    his   talents 

promise. 

JUSTUS  LIEBIG. 

Giessen,  September  1,  1840. 


EDITOR'S  PREFACE 


TO 


THE  SECOND  ENGLISH  EDITION. 


The  former  edition  of  this  work  was  prepared  in 
the  form  of  a  Report  on  the  present  state  of  Organic 
Chemistry.  The  state  of  a  science  such  as  this 
could  not  be  exhibited  by  a  systematic  treatise  on 
organic  compounds,  but  by  showing,  that  the  science 
was  so  far  advanced  as  to  be  useful  in  its  practical 
applications. 

The  work  was  written  by  a  Chemist,  and  address- 
ed to  Chemists.  The  author  did  not  flatter  himself, 
that  his  opinions  would  be  so  eagerly  embraced  by 
agriculturists,  as  circumstances  have  shown  to  be  the 
case.  Hence  his  language  and  style  were  less  adapt- 
ed for  them  than  for  those  who  are  conversant  with 
the  abstract  details  of  chemical  science.  But  the 
eager  reception  of  the  work  by  agriculturists  has 
shown,  that  they  possess  an  ardent  desire  to  profit 
by  the  aids  ofiered  to  them  by  Chemistry.  It,  there- 
fore, became  necessary  to  adapt  the  work  for  those 
who  have  not  had  an  opportunity  of  making  that 
science  a  peculiar  object  of  study. 

6* 


XVm  EDITOR'S  PREFACE  TO  THE 

The  Editor  has  endeavored  to  effect  this  change. 
In  doing  so,  it  was  necessary  to  retain  the  original 
character  of  the  work  ;  hence  those  alterations  only- 
have  been  made  which  are  calculated  to  render  the 
work  more  generally  useful.  It  must  be  remember- 
ed, that  the  object  of  the  author  was  not  to  write  a 
^^  System  of  Agricultural  Chemistry,"  but  to  furnish 
a  *^  Treatise  on  the  Chemistry  of  Agriculture."  It 
is  to  be  hoped,  that  those  who  are  acquainted  with 
the  general  doctrines  of  Chemistry  will  find  no  diffi- 
culty in  comprehending  any  of  the  principles  here 
developed. 

The  author  has  enriched  the  present  edition  with 
many  valuable  additions  ;  allusion  may  be  particular- 
ly made  to  the  practical  illustration  of  his  principles 
furnished  in  the  supplementary  Chapter  on  Soils. 
The  analyses  of  soils  contained  in  that  chapter  will 
serve  to  point  out  the  culpable  negligence  exhibited 
in  the  examination  of  English  soils.  Even  in  the 
analyses  of  professional  chemists,  published  in  detail, 
and  with  every  affectation  of  accuracy,  the  estima- 
tion of  the  most  important  ingredients  is  neglected. 
How  rarely  do  we  find  phosphoric  acid  amongst  the 
products  of  their  analyses  ?  potash  and  soda  would 
appear  to  be  absent  from  all  soils  in  the  British  ter- 
ritories !  Yet  these  are  invariable  constituents  of 
fertile  soils,  and  are  conditions  indispensable  to  their 
fertility. 

It  is  necessary  to  state,  that  all  additions  and  alter- 
ations, with  a  few  unimportant  exceptions,  have  been 


SECOND  ENGLISH  EDETION.  xix 

submitted  to  the  revision  of  the  author.  The  Index 
at  the  end  of  the  volume  has  been  principally  com- 
piled from  one  furnished  by  Professor  Webster,  of 
Harvard  University,  in  his  American  edition  of  this 
work.  The  editor  gladly  avails  himself  of  this  op- 
portunity to  thank  this  gentleman  for  the  care  and 
attention  which  he  has  displayed  in  superintending 
its  republication.  ' 

Primrose,  November  22,  1841. 


ORGANIC  CHEIISTEY 


IN  ITS  APPLICATION  TO 


VEGETABLE    PHYSIOLOGY  AND  AGRICULTURE. 


The  object  of  Chemistry  is  to  examine  into  the 
composition  of  the  numerous  modifications  of  mat- 
ter, which  occur  in  the  organic  and  inorganic  king- 
doms of  nature,  and  to  investigate  the  laws  by 
which  the  combination  and  decomposition  of  their 
parts  is  effected. 

Although  material  substances  assume  a  vast  vari- 
ety of  forms,  yet  chemists  have  not  been  able  to  de- 
tect more  than  fifty-five  bodies  which  are  simple,  or 
contain  only  one  kind  of  matter,  and  from  these  all 
other  substances  are  produced.  They  are  considered 
simple  only  because  it  has  not  been  proved  that  they 
consist  of  two  or  more  parts.  The  greater  number 
of  the  elements  occur  in  the  inorganic  kingdom. 
Four  only  are  found  in  organic  matter. 

But  it  is  evident  that  this  limit  to  their  number 
must  render  it  more  difficult  to  ascertain  the  precise 
circumstances,  under  which  their  union  is  effected, 
and  the  laws  which  regulate  their  combinations. 
Hence  chemists  have  only  lately  turned  their  atten- 
tion to  the  study  of  the  nature  of  bodies  generated 
by  organized  beings.  A  few  years  have,  however, 
sufficed  to  throw  much  light  upon  this  interesting 
department  of  science,  and  numerous  facts  have  been 
discovered  which  cannot  fail  to  be  of  importance  in 
their  practical  applications. 


22  CONDITIONS  ESSENTIAL  TO  NUTRITION. 

The  peculiar  object  of  organic  chemistry  *  is  to 
discover  the  chemical  conditions  essential  to  the  life 
and  perfect  development  of  animals  and  vegetables, 
and  generally  to  investigate  all  those  processes  of 
organic  nature  vsrhich  are  due  to  the  operation  of 
chemical  laws.  Now,  the  continued  existence  of  all 
living  beings  is  dependent  on  the  reception  by  them 
of  certain  substances,  which  are  applied  to  the  nu- 
trition of  their  frame.  An  inquiry,  therefore,  into 
the  conditions  on  which  the  life  and  growth  of  living 
beings  depend,  involves  the  study  of  those  substan- 
ces which  serve  them  as  nutriment,  as  well  as  the 
investigation  of  the  sources  whence  these  substances 
are  derived,  and  the  changes  which  they  undergo  in 
the  process  of  assimilation. 

A  beautiful  connexion  subsists  between  the  or- 
ganic and  inorganic  kingdoms  of  nature.  Inorganic 
matter  affords  food  to  plants,  and  they,  on  the  other 
hand,  yield  the  means  of  subsistence  to  animals. 
The  conditions  necessary  for  animal  and  vegetable 
nutrition  are  essentially  different.  An  animal  re- 
quires for  its  development,  and  for  the  sustenance 
of  its  vital  functions,  a  certain  class  of  substances 
which  can  only  be  generated  by  organic  beings  pos- 
sessed of  life.  Although  many  animals  are  entirely 
carnivorous,  yet  their  primary  nutriment  must  be 
derived  from  plants ;  for  the  animals  upon  which 
they  subsist  receive  their  nourishment  from  vegeta- 
ble matter.  But  plants  find  new  nutritive  material 
only  in  inorganic  substances.  Hence  one  great  end 
of  vegetable  life  is  to  generate  matter  adapted  for 
the  nutrition  of  animals  out  of  inorganic  substances, 
which  are  not  fitted  for  this  purpose.     Now  the  pur- 

*  Every  vegetable  and  animal  constitutes  a  machine  of  greater  or 
less  complexity,  composed  of  a  variety  of  parts  dependent  on  each 
other,  and  acting  all  of  them  to  produce  a  certain  end.  Vegetables  and 
animals,  on  this  account,  are  called  organized  beings ;  and  the  chemi- 
cal history  of  those  compounds  which  are  of  animal  or  vegetable  origin, 
or  of  organic  substances,  is  called  organic  chemistry.  See  Thomson's 
Chemistry  of  Organic  Bodies,  and  Webster's  Manual  of  Chemistry,  3d 
edit.,  p.  362. 


SUBJECT  OF  THE  WORK.  23 

port  of  this  work  is,  to  elucidate  the  chemical  pro- 
cesses engaged  in  the  nutrition  of  vegetables. 

The  first  part  of  it  will  be  devoted  to  the  exam- 
ination of  the  matters  which  supply  the  nutriment 
of  plants,  and  of  the  changes  which  these  matters 
undergo  in  the  living  organism.  The  chemical  com- 
pounds which  afford  to  plants  their  principal  con- 
stituents, viz.  carbon  and  nitrogen,  will  here  come 
under  consideration,  as  well  as  the  relations  in  which 
the  vital  functions  of  vegetables  stand  to  those  of  the 
animal  economy  and  to  other  phenomena  of  nature. 

The  second  part  of  the  work  will  treat  of  the 
chemical  processes  which  effect  the  complete  de- 
struction of  plants  and  animals  after  death,  such  as 
the  peculiar  modes  of  decomposition,  usually  de- 
scribed 2iS  fermentation,  putrefaction,  and  decay  ;  and 
in  this  part  the  changes  w^hich  organic  substances 
undergo  in  their  conversion  into  inorganic  com- 
pounds, as  well  as  the  causes  which  determine  these 
changes,  will  become  matter  of  inquiry. 


iimr 


PART  I. 

OF  THE  CHEMICAL  PROCESSES  IN  THE  NUTRITION 

OF  VEGETABLES. 


CHAPTER  L 

OF  THE  CONSTITUENT  ELEMENTS  OF  PLANTS. 

The  ultimate  constituents  of  plants  are  those  which 
form  organic  matter  in  general,  namely,  Carbon,  Hy- 
drogen, Nitrogen,  and  Oxygen.  These  elements  are 
always  present  in  plants,  and  produce  by  their  union 
the  various  proximate  principles  of  which  they  con- 
sist. It  is,  therefore,  necessary,  to  be  acquainted 
with  their  individual  characters,  for  it  is  only  by  a 
correct  appreciation  of  these  that  we  are  enabled  to 
explain  the  functions  which  they  perform  in  the  veg- 
etable organization. 

Carbon  is  an  elementary  substance,  endowed  with 
a  considerable  range  of  affinity.  With  oxygen  it 
unites  in  two  proportions,  forming  the  gaseous  com- 
pounds known  under  the  names  of  carbonic  acid  and 
carbonic  oxide.  The  former  of  these  is  emitted  in 
immense  quantities  from  many  volcanoes  and  mineral 
springs,  and  is  a  product  of  the  combustion  and  de- 
cay of  organic  matter.  It  is  subject  to  be  decom- 
posed by  various  agencies,  and  its  elements  then  ar- 
range themselves  into  new  combinations.  Carbon  is 
familiarly  known  as  charcoal^  but  in  this  state  it  is 
mixed  with  several  earthy  bodies ;  in  a  state  of  ab- 
solute purity  it  constitutes  the  diamond.* 

*  Wood  charcoal  contains  about  l-50th  of  its  weight  of  alkaline  and 
earthy  salts,  which  constitute  the  ashes  when  it  is  burned. 


OF  THE  CONSTITUENT  ELEMENTS  OF  PLANTS.  25 

Hydrogen  (^hiflammable  Air)  is  a  very  important 
constituent  of  vegetable  matter.  It  possesses  a 
special  affinity  for  oxygen,  with  which  it  unites  and 
forms  water.  The  whole  of  the  phenomena  of  decay 
depend  upon  the  exercise  of  this  affinity,  and  many 
of  the  processes  engaged  in  the  nutrition  of  plants 
originate  in  the  attempt  to  gratify  it.  Hydrogen, 
when  in  the  state  of  a  gas,  is  very  combustible,  and 
the  lightest  body  known ;  but  it  is  never  found  in 
nature  in  an  isolated  condition.  Water  is  the  most 
common  combination  in  which  it  is  presented ;  and 
it  may  be  removed  by  various  processes  from  the 
oxygen,  with  which  it  is  united  in  this  body. 

Nitrogen  *  is  quite  opposed  in  its  chemical  char- 
acters to  the  two  bodies  now  described.  Its  princi- 
pal characteristic  is  an  indifference  to  all  other  sub- 
stances, and  an  apparent  reluctance  to  enter  into 
combination  with  them.  When  forced  by  peculiar 
circumstances  to  do  so,  it  seems  to  remain  in  the 
combination  by  a  vis  inertice  ;  and  very  slight  forces 
effect  the  disunion  of  these  feeble  compounds. 

Yet  nitrogen  is  an  invariable  constituent  of  plants, 
and  during  their  life  is  subject  to  the  control  of  the 
vital  powers.     But  when  the  mysterious  principle  of 

*  This  gas  was  discovered  in  1772,  and  is  called  also  azote  or  azotic 
ffaSj  from  the  Greek,  expressive  of  its  being  incapable  of  supporting 
life.  The  name  Nitrogen  was  given  to  it  from  its  entering  into  the 
composition  of  nitric  acid  (aqua  fortis).  It  has  been  suspected  to  be  a 
compound,  but  this  has  not  been  verified.  The  atmosphere  is  compos- 
ed of  four  fifths  nitrogen  and  one  fifth  oxygen,  not,  however,  chemical- 
ly united  ;  it  also  contains  a  ten  thousandth  part  of  carbonic  acid  and 
watery  vapor.  A  mixture  of  oxygen  and  nitrogen  in  the  proportions 
named,  exhibits  the  general  properties  of  the  atmosphere.  Nitrogen 
may  be  obtained  from  common  air  by  removing  its  oxygen,  and  from 
the  lean  part  of  flesh  meat  by  boiling  it  in  diluted  nitric  acid.  It  unites 
with  different  proportions  of  oxygen,  and  forms  as  many  distinct  com- 
pounds, viz. 

^?n^'  f  S  Protoxide  of  Nitrogen,  nitrous 

i>U      torm   ^     oxide,  or  exhilarating  gas. 

^^      C  Binoxide  of  Nitrogen 

(      or  Nitric  oxide. 
"        Hyponitrous  acid. 
**         Nitrous  acid. 
"        Nitric  acid. 
For  other  details,  see  Webster's  Chemistry,  3d  edit.,  p.  134,  &c; 

3 


JVitrog. 
100 

+ 

50 

lOO 

+ 

100 

100 
100 
100 

+ 

150 
200 
250 

26  OF  THE  CONSTITUENT  ELEMENTS  OF  PLANTS. 

life  has  ceased  to  exercise  its  influence,  this  element 
resumes  its  chemical  character,  and  materially  assists 
in  promoting  the  decay  of  vegetable  matter,  by  es- 
caping from  the  compounds  of  which  it  formed  a 
constituent. 

Oxygen,  the  only  remaining  constituent  of  organic 
matter,  is  a  gaseous  element,  which  plays  a  most 
important  part  in  the  economy  of  nature.  It  is  the 
agent  employed  in  effecting  the  union  and  disunion 
of  a  vast  number  of  compounds.  It  is  superior  to 
all  other  elements  in  the  extensive  range  of  its  af- 
finities. The  phenomena  of  combustion  and  decay 
are  examples  of  the  exercise  of  its  power. 

Oxygen  is  the  most  generally  diffused  element  on 
the  surface  of  the  earth ;  for,  besides  constituting 
the  principal  part  of  the  atmosphere  which  surrounds 
it,  it  is  a  component  of  almost  all  the  earths  and 
minerals  found  on  its  surface.  In  an  isolated  state 
it  is  a  gaseous  body,  possessed  of  neither  taste  nor 
smell.  It  is  slightly  soluble  in  water,  and  hence  is 
usually  found  dissolved  in  rain  and  snow,  as  well  as 
in  the  water  of  running  streams. 

Such  are  the  principal  characters  of  the  elements 
which  constitute  organic  matter ;  but  it  remains  for 
us  to  consider  in  what  form  they  are  united  in  plants. 

The  substances  which  constitute  the  principal  mass 
of  every  vegetable  are  compounds  of  carbon  with  ox- 
ygen and  hydrogen,  in  the  proper  relative  propor- 
tions for  forming  water.  Woody  fibre,  starch,  sugar, 
and  gum,  for  example,  are  such  compounds  of  carbon 
with  the  elements  of  water.  In  another  class  of  sub- 
stances containing  carbon  as  an  element,  oxygen  and 
hydrogen  are  again  present ;  but  the  proportion  of 
oxygen  is  greater  than  would  be  required  for  produc- 
ing water  by  union  with  the  hydrogen.  The  numer- 
ous organic  acids  met  with  in  plants  belong,  with 
few  exceptions,  to  this  class. 

A  third  class  of  vegetable  compounds  contains  car- 
bon and  hydrogen,  but  no  oxygen,  or  less  of  that 
element  than  would  be  required  to  convert  all  the 


OF  THE  COMPOSITION  OF  THE  ATMOSPHERE.  27 

hydrogen  into  water.  These  may  be  regarded  as 
compounds  of  carbon  with  the  elements  of  water, 
and  an  excess  of  hydrogen.  Such  are  the  volatile 
and  fixed  oils,  wax,  and  the  resins.  Many  of  them 
have  acid  characters. 

The  juices  of  all  vegetables  contain  organic  acids, 
generally  combined  with  the  inorganic  bases,  or  me- 
tallic oxides  I  for  these  metallic  oxides  exist  in 
every  plant,  and  may  be  detected  in  its  ashes  after 
incineration. 

Nitrogen  is  an  element  of  vegetable  albumen  and 
gluten ;  it  is  a  constituent  of  the  acid,  and  of  what 
are  termed  the  "  indifferent  substances  "  of  plants, 
as  well  as  of  those  peculiar  vegetable  compounds 
which  possess  all  the  properties  of  metallic  oxides, 
and  are  known  as  "  organic  bases." 

Estimated  by  its  proportional  weight,  nitrogen 
forms  only  a  very  small  part  of  plants ;  but  it  is 
never  entirely  absent  from  any  part  of  them.  Even 
when  it  does  not  absolutely  enter  into  the  composi- 
tion of  a  particular  part  or  organ,  it  is  always  to  be 
found  in  the  fluids  which  pervade  it. 

It  follows  from  the  facts  thus  far  detailed,  that 
the  development  of  a  plant  requires  the  presence, 
first,  of  substances  containing  carbon  and  nitrogen, 
and  capable  of  yielding  these  elements  to  the  grow- 
ing organism ;  secondly,  of  water  and  its  elements  ; 
and  lastly,  of  a  soil  to  furnish  the  inorganic  matters 
which  are  likewise  essential  to  vegetable  life. 


OF    THE    COMPOSITION    OF    THE    ATMOSPHERE. 

In  the  normal  state  of  growth,  plants  can  only 
derive  their  nourishment  from  the  atmosphere  and 
the  soil.  Hence  it  is  of  importance  to  be  acquainted 
with  the  composition  of  these,  in  order  that  we  may 
be  enabled  to  judge  from  which  of  their  constituents 
the  nourishment  is  afforded. 

The  composition  of  the  atmosphere  has  been  exam- 


28  OF  THE  COMPOSITION  OF  THE  ATMOSPHERE. 

ined  by  many  chemists  with  great  care,  and  the  results 
of  their  researches  have  shown,  that  its  principal 
constituents  are  always  present  in  the  same  propor- 
tion. These  are  the  two  gases,  oxygen  and  nitro- 
gen, the  general  properties  of  which  have  been 
already  described.  One  hundred  parts,  by  weight, 
of  atmospheric  air  contain  23*1  parts  of  oxygen, 
and  76*9  parts  of  nitrogen ;  or  100  volumes  of  air 
contain  nearly  21  volumes  of  oxygen  gas.  From 
the  extensive  range  of  affinity  which  this  gas  pos- 
sesses, it  is  obvious,  that  were  it  alone  to  constitute 
our  atmosphere,  and  left  unchecked  to  exert  its 
powerful  effects,  all  nature  would  be  one  scene  of 
universal  destruction.  It  is  on  this  account  that 
nitrogen  is  present  in  the  air  in  so  large  proportion. 
It  is  peculiarly  adapted  for  this  purpose,  as  it  does 
not  possess  any  disposition  to  unite  with  oxygen, 
and  exerts  no  action  upon  the  processes  proceeding 
on  the  earth.  These  two  gases  are  intimately  mixed, 
by  virtue  of  a  property  which  all  gases  possess  in 
common,  of  diffusing  themselves  equally  through 
every  part  of  another  gas,  with  which  they  are 
placed  in  contact. 

Although  oxygen  and  nitrogen  form  the  principal 
constituents  of  the  atmosphere,  yet  they  are  not  the 
only  substances  found  in  it.  Watery  vapor  and 
carbonic  acid  gas  materially  modify  its  properties. 
The  former  of  these  falls  upon  the  earth  as  rain,  and 
brings  with  it  any  soluble  matter  which  it  meets  in 
its  passage  through  the  air. 

Carbonic  acid  gas  is  discharged  in  immense  quan- 
tities from  the  active  volcanoes  of  America,  and 
from  many  of  the  mineral  springs  which  abound  in 
various  parts  of  Europe;  it  is  also  generated  during 
the  combustion  and  decay  of  organic  matter.  It  is 
not,  therefore,  surprising  that  it  should  have  been 
detected  in  every  part  of  the  atmosphere  in  which 
its  presence  has  been  looked  for.  Saussure  found  it 
even  in  the  air  on  the  summit  of  Mont  Blanc,  which 
is  covered  with  perpetual  snow,  and  where  it  could 


OF  SOILS.  29 

not  have  been  produced  by  the  immediate  agency  of 
vegetable  matter.  Carbonic  acid  gas  performs  a 
most  important  part  in  the  process  of  vegetable 
nutrition,  the  consideration  of  which  belongs  to 
another  part  of  the  work. 

Carbonic  acid,  water,  and  ammonia  (a  compound 
of  hydrogen  and  nitrogen)  are  the  final  products  of 
the  decay  of  animal  and  vegetable  matter.  In  an 
isolated  condition,  they  usually  exist  in  the  gaseous 
form.  Hence,  on  their  formation,  they  must  escape 
into  the  atmosphere.  But  ammonia  has  not  hitherto 
been  enumerated  amongst  the  constituents  of  the 
air,  although,  according  to  our  view,  it  can  never  be 
absent.  The  reason  of  this  is,  that  it  exists  in 
extremely  minute  quantity  in  the  amount  of  air  usu- 
ally subjected  to  experiment  in  chemical  analysis; 
it  has  consequently  escaped  detection.  But  rain 
which  falls  through  a  large  extent  of  air,  carries 
down  in  solution  all  that  remains  in  suspension  in  it. 
Now  ammonia  always  exists  in  rain-water,  and  from 
this  fact  we  must  conclude  that  it  is  invariably  pres- 
ent in  the  atmosphere.  Nor  can  we  be  surprised  at 
its  presence  when  we  consider  that  many  volcanoes 
now  in  activity  emit  large  quantities  of  it.*  This 
subject  will,  however,  be  discussed  more  fully  in 
another  part  of  the  work. 

Such  are  the  principal  constituents  of  the  atmo- 
sphere from  which  plants  derive  their  nourishment; 
for  although  other  matters  are  supposed  to  exist  in 
it  in  minute  quantity,  yet  they  do  not  exercise  any 
influence  on  vegetation,  nor  has  even  their  presence 
been  satisfactorily  demonstrated. 


OF    SOILS. 


A  soil  may  be  considered  a  magazine  of  inorganic 
matters,  which  are  prepared  by  the   plant  to  suit  the 

*  The  annual  evolution  of  carbonic  acid  from  springs  and  fissures  in  the 
ancient  volcanic  district  of  the  Eifel,  on  the  Rhine,  has  been  estimated  by 
Bischof,  at  not  less  than  100,000  tons,  containing  27,000  tons  of  carbon. 

3# 


30  OF  THE  ASSIMILATION  OF  CARBON. 

purposes  for  which  they  are  destined  in  its  nutrition. 
The  composition  and  uses  of  such  substances  cannot, 
however,  be  studied  with  advantage,  until  we  have 
considered  the  manner  in  w^hich  the  organic  matter 
is  obtained  by  plants. 

Some  virgin  soils,  such  as  those  of  America,  con- 
tain vegetable  matter  in  large  proportion ;  and  as 
these  have  been  found  eminently  adapted  for  the 
cultivation  of  most  plants,  the  organic  matter  con- 
tained in  them  has  naturally  been  recognised  as  the 
cause  of  their  fertility.  To  this  matter,  the  term 
"  vegetable  mould  '^  or  humus  has  been  applied. 
Indeed,  this  peculiar  substance  appears  to  play  such 
an  important  part  in  the  phenomena  of  vegetation, 
that  vegetable  physiologists  have  been  induced  to 
ascribe  the  fertility  of  every  soil  to  its  presence.  It 
is  believed  by  many  to  be  the  principal  nutriment  of 
plants,  and  is  supposed  to  be  extracted  by  them 
from  the  soil  in  which  they  grow.  It  is  itself  the 
product  of  the  decay  of  vegetable  matter,  and  must 
therefore  contain  many  of  the  constituents  which 
are  found  in  plants  during  life.  Its  action  will 
therefore  be  examined  in  considering  whence  these 
constituents  are  derived. 


CHAPTER   II. 

OF  THE  ASSIMILATION  OF   CARBON. 


COMPOSITION    OF    HUMUS. 

The  humus,  to  which  allusion  has  been  made,  is 
described  by  chemists  as  a  brown  substance  easily 
soluble  in  alkalies,  but  only  slightly  so  in  water,  and 
produced  during  the  decomposition  of  vegetable 
matters  by  the  action  of  acids  or  alkalies.  It  has, 
however,  received  various  names  according  to  the 
different  external  characters  and  chemical  properties 
which  it  presents.     Thus,  ulmin,  humic  acid,  coal  of 


N 


COMPOSITION  OF  HUMUS.  31 

humus,  and  humiii,  are  names  applied  to  modifica- 
tions of  humus.  They  are  obtained  by  treating  peat, 
woody  fibre,  soot,  or  brown  coal  with  alkalies  ;  by 
decomposing  sugar,  starch,  or  sugar  of  milk  by 
means  of  acids  ;  or  by  exposing  alkaline  solutions  of 
tannic  and  gallic  acids  to  the  action  of  the  air. 

The  modifications  of  humus  which  are  soluble  in 
alkalies,  are  called  humic  acid;  while  those  which 
are  insoluble  have  received  the  designations  of  humin 
and  coal  of  humus* 

The  names  given  to  these  substances  might  cause 
it  to  be  supposed  that  their  composition  is  identical. 
But  a  more  erroneous  notion  could  not  be  enter- 
tained ;  since  even  sugar,  acetic  acid,  and  resin  do 
not  differ  more  widely  in  the  proportions  of  their 
constituent  elements,  than  do  the  various  modifica- 
tions of  humus. 

Humic  acid  formed  by  the  action  of  hydrate  f  of 

*  The  soluble  matters  were  formerly  called  by  the  eminent  Swedish 
chemist  Berzelius,  extract  of  humuSy  and  the  insoluble  geine  (from  the 
Greek  y?7,  the  earth) ,  also  apotheme  and  carbonaceous  humus.  This 
substance  is  now  known  to  be  composed  of  various  ingredients,  and  of 
these  the  two  acids,  which  have  received  the  names  of  Crenic  and 
^pocrenic,  are  particularly  interesting. 

See  Professor  Hitchcock's  Report,  and  American  Journal  of  Science, 
Vol.  XXXVL,  Art.  XII. 

Dr.  S.  L.  Dana  considers  geine  as  forming  the  basis  of  all  the  nour- 
ishing part  of  all  vegetable  manures,  and,  in  the  three  states  of"  vegeta- 
ble extract,  geine,  and  carbonaceous  mould,"  to  be  the  principle  which 
gives  fertility  to  soils  long  after  the  action  of  common  manures  has 
ceased.  See  Report  on  the  reexamination  of  the  Economical  Geology 
of  Massachusetts.  In  the  Third  Report  on  the  Agriculture  of  the  State 
of  Massachusetts f  1840,  Dr.  Dana  remarks,  that  geine  "is  the  decom- 
posed organic  matter  of  the  soil.  It  is  the  product  of  putrefaction ; 
continually  subjected  to  air  and  moisture,  it  is  finally  wholly  dissipated 
in  air,  leaving  only  the  inorganic  bases  of  the  plant,  with  which  it  was 
once  combined.  Now,  whetner  we  consider  this  as  a  simple  substance, 
or  composed  of  several  others,  called  crenic,  apocrenic,  puteanic,  ulmic 
acids,  glairin,  apotheme,  extract,  humus,  or  mould,  agriculture  ever 
has  and  probably  ever  will  consider  it  one  and  the  same  thing,  requir- 
ing always  similar  treatment  to  produce  it;  similar  treatment  to  render 
it  soluble  when  produced ;  similar  treatment  to  render  it  an  effectual 
manure.  It  is  the  end  of  all  compost  heaps  to  produce  soluble  geine, 
no  matter  how  compound  our  chemistry  may  teach  this  substance  to 
be."    Page  191. 

f  Hydrates  are  compounds  of  oxides,  salts,  &c.,  with  definite  quan- 
tities of  water, —  a  substance  from  wlych  all  the  water  has  been  re- 
moved is  anhydrous.  Even  after  exposure  to  a  red  heat,  caustic  potash 
retains  water. 


32  OF  THE  ASSIMILATION  OF  CARBON. 

potash  upon  sawdust  contains,  according  to  the 
accurate  analysis  of  Peligot,  72  per  cent,  of  carbon, 
while  the  humic  acid  obtained  from  turf  and  brown 
coal  contains,  according  to  Sprengel,  only  58  per 
cent. ;  that  produced  by  the  action  of  dilute  sul- 
phuric acid  upon  sugar,  57  per  cent,  according  to 
Malaguti ;  and  that,  lastly,  which  is  obtained  from 
sugar  or  from  starch,  by  means  of  muriatic  acid, 
according  to  the  analysis  of  Stein,  64  per  cent.  All 
these  analyses  have  been  repeated  with  care  and 
accuracy,  and  the  proportion  of  carbon  in  the  re- 
spective cases  has  been  found  to  agree  with  the 
estimates  of  the  different  chemists  above  mentioned; 
so  that  there  is  no  reason  to  ascribe  the  difference 
in  this  respect  between  the  varieties  of  humus  to 
the  mere  difference  in  the  methods  of  analysis  or 
degrees  of  expertness  of  the  operators.  Malaguti 
states,  moreover,  that  humic  acid  contains  an  equal 
number  of  equivalents  of  oxygen  and  hydrogen,  that 
is  to  say,  that  these  elements  exist  in  it  in  the  pro- 
portions for  forming  water ;  while,  according  to 
Sprengel,  the  oxygen  is  in  excess,  and  Peligot  even 
estimates  the  quantity  of  oxygen  at  14  equivalents, 
and  the  hydrogen  at  only  6  equivalents,  making  the 
deficiency  of  hydrogen  as  great  as  8  equivalents. 
And  although  Mulder  *  has  very  recently  explained 
many  of  these  conflicting  results,  by  showing  that 
there  are  several  kinds  of  humus  and  humic  acids 
essentially  distinct  in  their  characters,  and  fixed  in 
their  composition,  yet  he  has  afforded  no  proof  that 
the  definite  compounds  obtained  by  him  really  exist, 
as  such,  in  the  soil.  On  the  contrary,  they  appear 
to  have  been  formed  by  the  action  of  the  potash  and 
ammonia,  which  he  employed  in  their  preparation. 

It  is  quite  evident,  therefore,  that  chemists  have 
been  in  the  habit  of  designating  all  products  of  the 
decomposition  of  organic  bodies  which  had  a  brown 
or    brownish-black,   color    by  the    names  of   humic 


*  Bulletin  des  Scienc.  Phys.  et  Natur.  de  Neerl.  1840,  p.  1-102. 


PROPERTIES  OF  HUMUS.  33 

acid  or  hiimin,  according  as  they  were  soluble  or 
insoluble  in  alkalies ;  although  in  their  composition 
and  mode  of  origin,  the  substances  thus  confounded 
might  be  in  no  way  allied. 

Not  the  slightest  ground  exists  for  the  belief  that 
one  or  other  of  these  artificial  products  of  the  de- 
composition of  vegetable  matters  exists  in  nature  in 
the  form  and  endowed  with  the  properties  of  the 
vegetable  constituents  of  mould;  there  is  not  the 
shadow  of  a  proof  that  one  of  them  exerts  any  influ- 
ence on  the  growth  of  plants  either  in  the  way  of 
nourishment  or  otherwise. 

Vegetable  physiologists  have,  without  any  appar- 
ent reason,  imputed  the  known  properties  of  the 
humus  and  humic  adds  of  chemists  to  that  constitu- 
ent of  mould  which  has  received  the  same  name,  and 
L  in  this  way  have  been  led  to  their  theoretical  notions 
'■  respecting  the  functions  of  the  latter  substance  in 
vegetation. 

The  opinion,  that  the  substance  called  humus  is 
extracted  from  the  soil  by  the  roots  of  plants,  and 
that  the  carbon  entering  into  its  composition  serves 
in  some  form  or  other  to  nourish  their  tissues,  is 
considered  by  many  as  so  firmly  established,  that  any 
new  argument  in  its  favor  has  been  deemed  unneces- 
sary; the  obvious  difference  in  the  growth  of  plants, 
according  to  the  known  abundance  or  scarcity  of 
humus  in  the  soil,  seemed  to  afford  incontestable 
proof  of  its  correctness.''^ 

Yet,  this  position,  when  submitted  to  a  strict  ex- 
amination, is  found  to  be  untenable,  and  it  becomes 
evident,  from  most  conclusive  proofs,  that  humus,  in 
the  form  in  which  it  exists  in  the  soil,  does  not  yield 
the  smallest  nourishment  to  plants. 

The  adherence  to  the  above  incorrect  opinion  has 


*  This  remark  applies  more  to  German  than  to  English  botanists  and 
physiologists.  In  England,  the  idea  that  humus,  as  such,  affords  nour- 
ishment to  plants  is  by  no  means  general ;  but  on  the  Continent,  the 
views  of  Berzelius  on  this  subject  have  been  almost  universally  adopt- 
ed.—Ed. 


34  OF  THE  ASSIMILATION  OF  CARBON. 

hitherto  rendered  it  impossible  for  the  true  theory 
of  the  nutritive  process  in  vegetables  to  become 
known,  and  has  thus  deprived  us  of  our  best  guide 
to  a  rational  practice  in  agriculture.  Any  great  im- 
provement in  that  most  important  of  all  arts  is  in- 
conceivable, without  a  deeper  and  more  perfect  ac- 
quaintance with  the  substances  which  nourish  plants, 
and  with  the  sources  whence  they  are  derived  ;  and 
no  other  cause  can  be  discovered  to  account  for  the 
fluctuating  and  uncertain  state  of  our  knowledge  on 
this  subject  up  to  the  present  time,  than  that  modern 
physiology  has  not  kept  pace  with  the  rapid  progress 
of  chemistry. 

In  the  following  inquiry, we  shall  suppose  the  hu- 
mus of  vegetable  physiologists  to  be  really  endowed 
with  the  properties  recognised  by  chemists  in  the 
brownish  black  deposits,  which  they  obtain  by  pre- 
cipitating an  alkaline  decoction  of  mould  or  peat  by 
means  of  acids,  and  which  they  name  humic  acid,^ 

Humic  acid,  when  first  precipitated,  is  a  flocculent 
substance,  is  soluble  in  2500  times  its  weight  of  wa- 
ter, and  combines  with  alkalies,  lime  and  magnesia, 
forming  compounds  of  the  same  degree  of  solubility. 
(Sprengel.) 

Vegetable  physiologists  agree  in  the  supposition 
that  by  the  aid  of  water  humus  is  rendered  capable . 

*  The  extract  obtained  by  Berzelius  from  black-  brownish  soils  has 
been  designated  as  humic  extract,  in  some  cases  with  a  substance  called 
glairin.  The  glairin  is  described  by  Thomson  as  a  peculiar  substance 
which  has  been  observed  in  certain  sulphureous  mineral  waters,  and 
was  first  noticed  by  Vauquelin  {Jinn,  de  Chim.  XXXIX.  173),  who  de- 
scribed several  of  its  properties  and  considered  it  analogous  to  gelatin. 
An  account  of  it  was  drawn  up  by  M.  Anglada,  of  Montpellier,  and 
communicated  to  the  Royal  Academy  of  Medicine  of  Paris,  in  1827.  It 
gelatinizes  with  water  when  sufficiently  concentrated.  Sometimes  it  is 
white,  and  at  others  of  a  red  color;  when  dried  it  shrinks  to  ^th  of  its 
bulk  when  moist.  It  saturates  ammonia,  and  decomposes  several  me- 
tallic salts.  It  is  destitute  of  smell  and  taste.  It  does  not  glne  sub- 
stances together  like  gelatin  and  albumen.  It  yields  animonia  by  de- 
composition, and  is  capable  of  putrefaction  like  animal  bodies.  The 
general  opinion  is,  that  it  is  of  vegetable  origin,  and  allied  to  the  genUs 
tremella,  though  its  existence  in  mineral  waters  has  not  been  account- 
ed for.  Thomson's  Oraranic  Chemistry,  694.  I  found  it  very  abun- 
dant about  the  hot  sulphureous  waters  of  the  island  of  St.  Michael, 
Azores.  —  IV, 


ABSORPTION  OF  HUMUS.  35 

of  being  absorbed  by  the  roots  of  plants.  But  ac- 
cording to  the  observation  of  chemists,  humic  acid  is 
soluble  only  when  newly  precipitated,  and  becomes 
completely  insoluble  when  dried  in  the  air,  or  when 
exposed  in  the  moist  state  to  the  freezing  tempera- 
ture.    (Sprengel.) 

Both  the  cold  of  winter  and  the  heat  of  summer 
therefore  are  destructive  of  the  solubility  of  humic 
acid,  and  at  the  same  time  of  its  capability  of  being 
assimilated  by  plants.  So  that,  if  it  is  absorbed  by 
plants,  it  must  be  in  some  altered  form. 

The  correctness  of  these  observations  is  easily 
demonstrated  by  treating  a  portion  of  good  mould 
with  cold  water.  The  fluid  remains  colorless,  and  is 
found  to  have  dissolved  less  than  100,000  part  of  its 
weight  of  organic  matters,  and  to  contain  merely  the 
salts  which  are  present  in  rain-water. 

Decayed  oak-wood,  likewise,  of  which  humic  acid 
is  the  principal  constituent,  was  found  by  Berzelius 
to  yield  to  cold  water  only  slight  traces  of  soluble 
materials ;  and  I  have  myself  verified  this  observa- 
tion on  the  decayed  wood  of  beech  and  fir. 

These  facts,  which  show  that  humic  acid,  in  its 
unaltered  condition,  cannot  serve  for  the  nourishment 
of  plants,  have  not  escaped  the  notice  of  physiolo- 
gists ;  and  hence  they  have  assumed  that  the  lime  or 
the  diff*erent  alkalies,  found  in  the  ashes  of  vegeta- 
bles,render  soluble  the  humic  acid  and  fit  it  for  the 
process  of  assimilation. 

Alkalies  and  alkaline  earths  do  exist  in  the  differ- 
ent kinds  of  soil  in  sufficient  quantity  to  form  such 
soluble  compounds  with  the  humic  acid. 

Now,  let  us  suppose  that  humic  acid  is  absorbed 
by  plants  in  the  form  of  that  salt  which  contains  the 
largest  proportion  of  humic  acid,  namely,  in  the  form 
of  humate  of  lime,  and  then,  from  the  known  quantity 
of  the  alkaline  bases  contained  in  the  ashes  of  plants, 
let  us  calculate  the  amount  of  humic  acid  which 
might  be  assimilated  in  this  manner.  Let  us  admit, 
likewise,  that  potash,  soda,  and  the  oxides  of  iron 


36  OF  THE  ASSIMILATION  OF  CARBON. 

and  manganese  have  the  same  capacity  of  saturation 
as  lime  with  respect  to  humic  acid,  and  then  we  may 
take  as  the  basis  of  our  calculation  the  analysis  of 
M.  Berthier,  who  found  that  1000  lbs.  of  dry  fir-wood 
yielded  4  lbs.  of  ashes,  and  that  in  every  100  lbs.  of 
these  ashes,  after  the  chloride  of  potassium  and  sul- 
phate of  potash  were  extracted,  53  lbs.  consisted  of 
the  basic  metallic  oxides,  potash,  soda,  lime,  magne- 
sia, iron,  and  manganese. 

One  Hessian  acre*  of  woodland  yields  annually, 
according  to  Dr.  Heyer,  on  an  average,  2920  lbs.  of 
dry  fir-wood,  which  contain  6.17  lbs.  of  metallic 
oxides. 

Now,  according  to  the  estimates  of  Malaguti  and 
Sprengel,  1  lb.  of  lime  combines  chemically  with  12 
lbs.  of  humic  acid;  6.17  lbs.  of  the  metallic  oxides 
would  accordingly  introduce  into  the  trees  74.04  of 
humic  acid,  which,  admitting  humic  acid  to  contain 
58  per  cent,  of  carbon,  would  correspond  to  100  lbs. 
of  dry  wood.  But  we  have  seen  that  2920  lbs.  of 
fir-wood  are  really  produced. 

Again,  if  the  quantity  of  humic  acid  which  might 
be  introduced  into  wheat  in  the  form  of  humates  is 
calculated  from  the  known  proportion  of  metallic 
oxides  existing  in  wheat  straw,  (the  sulphates  and 
chlorides  also  contained  in  the  ashes  of  the  straw 
not  being  included,)  it  will  be  found  that  the  wheat 
growing  on  1  Hessian  acre  would  receive  in  that 
way  63  lbs.  of  humic  acid,  corresponding  to  93.6  lbs. 
of  woody  fibre.  But  the  extent  of  land  just  men- 
tioned produces,  independently  of  the  roots  and 
grain,  1961  lbs.  of  straw,  the  composition  of  which 
is  the  same  as  that  of  woody  fibre. 

It  has  been  taken  for  granted  in  these  calculations 
that  the  basic  metallic  oxides  which  have  served  to 
introduce  humic  acid  into  the  plants  do  not  return 
to  the  soil,  since  it  is  certain  that  they  remain  fixed 

*  One  Hessian  acre  is  equal  to  40,000  square  feet,  Hessian,  or  26,910 
square  feet,  English  measure.  —  P. 


ABSORPTION  OF  HUMUS.  37 

in  the  parts   newly  formed  during  the  process  of 
growth. 

Let  us  now  calculate  the  quantity  of  humic  acid 
which  plants  can  receive  under  the  most  favorable 
circumstances,  viz.,  through  the  agency  of  rain- 
water. 

The  quantity  of  rain  which  falls  at  Erfurt,  one  of 
the  most  fertile  districts  of  Germany,  during  the 
months  of  April,  May,  June,  and  July,  is  stated  by 
Schubler  to  be  19.3  lbs.  over  every  square  foot  of 
surface;  1  Hessian  acre,  or  26,910  square  feet,  con- 
sequently receive  519,363  lbs.  of  rain-water. 

If,  now,  we  suppose  that  the  whole  quantity  of 
this  rain  is  taken  up  by  the  roots  of  a  summer  plant, 
which  ripens  four  months  after  it  is  planted,  so  that 
not  a  pound  of  this  water  evaporates  except  from 
the  leaves  of  the  plant ;  and  if  we  further  assume 
that  the  water  thus  absorbed  is  saturated  with 
humate  of  lime  (the  most  soluble  of  the  humates, 
and  that  which  contains  the  largest  proportion  of 
humic  acid) ;  then  the  plants  thus  nourished  would 
not  receive  more  than  330  lbs.  of  humic  acid,  since 
one  part  of  humate  of  lime  requires  2500  parts  of 
water  for  solution. 

But  the  extent  of  land  which  we  have  mentioned 
produces  2843  lbs.  of  corn  (in  grain  and  straw,  the 
toots  not  included),  or  22,000  lbs.  of  beet-root 
(without  the  leaves  and  small  radical  fibres).  It  is 
quite  evident  that  the  330  lbs.  of  humic  acid,  sup- 
posed to  be  absorbed,  cannot  account  for  the  quan- 
tity of  carbon  contained  in  the  roots  and  leaves 
alone,  even  if  the  supposition  were  correct,  that  the 
whole  of  the  rain-water  was  absorbed  by  the  plants. 
But  since  it  is  known  that  only  a  small  portion  of 
the  rain-water  which  falls  upon  the  surface  of  the 
earth  evaporates  through  plants,  the  quantity  of 
carbon  which  can  be  conveyed  into  them  in  any 
conceivable  manner  by  means  of  humic  acid  must  be 
extremely  trifling,  in  comparison  with  that  actually 
produced  in  vegetation. 

4 


38  OF  THE  ASSIMILATION  OF  CARBON. 

Other  considerations  of  a  higher  nature  confute 
the  common  view  respecting  the  nutritive  office  of 
humic  acid,  in  a  manner  so  clear  and  conclusive  that 
it  is  difficult  to  conceive  how  it  could  have  been  so 
generally  adopted. 

Fertile  land  produces  carbon  in  the  form  of  wood, 
hay,  grain,  and  other  kinds  of  growth,  the  masses 
of  which  differ  in  a  remarkable  degree. 

2920  lbs.  of  firs,  pines,  beeches,  &c.  grow  as  wood 
upon  one  Hessian  acre  of  forest-land  with  an  average 
soil.     The  same  superficies  yields  2755  lbs.  of  hay. 

A  similar  surface  of  corn-land  gives  from  19,000 
to  22,004  lbs.  of  beet-root,  or  881  lbs.  of  rye,  and 
1961  lbs.  of  straw,  160  sheaves  of  15.4  lbs.  each, — 
in  all,  2843  lbs. 

One  hundred  parts  of  dry  fir-wood  contain  38 
parts  of  carbon;  therefore,  2920  lbs.  contain  1109 
lbs.  of  carbon. 

One  hundred  parts  of  hay,*"  dried  in  air,  contain 
44.31  parts  carbon.  Accordingly,  2755  lbs.  of  hay 
contain  1110  lbs.  of  carbon. 

Beet-roots  contain  from  89  to  89.5  parts  water, 
and  from  10.5  to  11  parts  solid  matter,  which  con- 
sists of  from  8  to  9  per  cent,  sugar,  and  from  2  to 
2i  per  cent,  cellular  tissue.  Sugar  contains  42.4 
per  cent.;  cellular  tissue,  47  per  cent,  of  carbon. 

22,004  lbs.  of  beet-root,  therefore,  if  they  contain 
9  per  cent,  of  sugar,  and  2  per  cent,  of  cellular  tis- 
sue, would  yield  1031  lbs.  of  carbon,  of  which  833 
lbs.  would  be  due  to  the  sugar,  and  198  lbs.  to  the 
cellular  tissue ;  the  carbon  of  the  leaves  and  small 
roots  not  being  included  in  the  calculation. 

One  hundred  parts  of  straw,!  dried  in  air,  contain 

*  100  parts  of  hay,  dried  at  100°  C.  (212<=  F.)  and  burned  with  oxide 
of  copper  in  a  stream  of  oxygen  gas,  yielded  51-93  water,  165'8  car- 
bonic acid,  and  682  of  ashes.  This  gives  45-87  carbon,  576  hydrogen, 
31*55  oxygen,  and  682  ashes.  Hay,  dried  in  the  air,  loses  11-2  p.  c. 
water  at  100°  C.  (212  F.  )  —  {Dr.  Will.) 

t  Straw  analyzed  in  the  same  manner,  and  dried  at  100°  C,  gave 
4637  p.  c.  of  carbon,  5-68  p.  c.  of  hydrogen,  43-93  p.  c.  of  oxygen,  and 
4-02  p.  c.  of  ashes.  Straw  dried  in  the  air  at  100°  C.  lost  18  p.  c.  of 
water.  — (i?r.  mil.) 


FERTILITY  OF  DIFFERENT  SOILS.  39 

38  per  cent,  of  carbon;  therefore  1961  lbs.  of  straw 
contain  745  lbs.  of  carbon.  One  hundred  parts  of 
corn  contain  43  parts  of  carbon;  882  lbs.  must 
therefore  contain  379  lbs.,  —  in  all,  1124  lbs.  of  car- 
bon. 

26,910  square  feet  of  wood  and  meadow  land  pro- 
duce, consequently,  1109  lbs.  of  carbon;  while  the 
same  extent  of  arable  land  yields  in  beet-root, 
without  leaves,  1032  lbs.,  or  in  corn,  1124  lbs. 

It  must  be  concluded  from  these  incontestable 
facts,  that  equal  surfaces  of  cultivated  land  of  an 
average  fertility  produce  equal  quantities  of  carbon ; 
yet,  how  unlike  have  been  the  different  conditions 
of  the  growth  of  the  plants  from  which  this  has 
been  deduced ! 

Let  us  now  inquire  whence  the  grass  in  a  meadow, 
or  the  wood  in  a  forest,  receives  its  carbon,  since 
there  no  manure  —  no  carbon  —  has  been  given  to  it 
as  nourishment  ?  and  how  it  happens,  that  the  soil, 
thus  exhausted,  instead  of  becoming  poorer,  becomes 
every  year  richer  in  this  element  ? 

A  certain  quantity  of  carbon  is  taken  every  year 
from  the  forest  or  meadow,  in  the  form  of  wood  or 
hay,  and,  in  spite  of  this,  the  quantity  of  carbon  in 
the  soil  augments  ;  it  becomes  richer  in  humus. 

It  is  said  that  in  fields  and  orchards  all  the  carbon 
which  may  have  been  taken  away  as  herbs,  as  straw, 
as  seeds,  or  as  fruit,  is  replaced  by  means  of  manure; 
and  yet  this  soil  produces  no  more  carbon  than  that 
of  the  forest  or  meadow,  where  it  is  never  replaced. 
It  cannot  be  conceived  that  the  laws  for  the  nutri- 
tion of  plants  are  changed  by  culture,  —  that  the 
sources  of  carbon  for  fruit  or  grain,  and  for  grass  or 
trees,  are  different. 

It  is  not  denied  that  manure  exercises  an  influence 
upon  the  development  of  plants;  but  it  may  be 
affirmed  with  positive  certainty,  that  it  neither  serves 
for  the  production  of  the  carbon, 'nor  has  any  influ- 
ence upon  it,  because  we  find  that  the  quantity  of 
carbon  produced  by  manured  lands  is  not    greater 


40  OF  THE  ASSIMILATION  OF  CARBON. 

than  that  yielded  by  lands  which  are  not  manured. 
The  discussion  as  to  the  manner  in  which  manure 
acts  has  nothing  to  do  with  the  present  question, 
which  is,  the  origin  of  the  carbon.  The  carbon  must 
be  derived  from  other  sources ;  and  as  the  soil  does 
not  yield  it,  it  can  only  be  extracted  from  the  atmo- 
sphere. 

In  attempting  to  explain  the  origin  of  carbon  in 
plants,  it  has  never  been  considered  that  the  ques- 
tion is  intimately  connected  with  that  of  the  origin 
of  humus.  It  is  universally  admitted  that  humus 
arises  from  the  decay  of  plants.  No  primitive 
humus,  therefore,  can  have  existed, —  for  plants  must 
have  preceded  the  humus. 

Now,  whence  did  the  first  vegetables  derive  their 
carbon  ?  and  in  what  form  is  the  carbon  contained 
in  the  atmosphere  ? 

These  two  questions  involve  the  consideration  of 
twt)  most  remarkable  natural  phenomena,  which  by 
their  reciprocal  and  uninterrupted  influence  maintain 
the  life  of  the  individual  animals  and  vegetables, 
and  the  continued  existence  of  both  kingdoms  of 
organic  nature. 

One  of  these  questions  is  connected  with  the  inva- 
riable condition  of  the  air  with  respect  to  oxygen. 
One  hundred  volumes  of  air  have  been  found,  at 
every  period  and  in  every  climate,  to  contain  21 
volumes  of  oxygen,  with  such  small  deviations  that 
they  must  be  ascribed  to  errors  of  observation. 

Although  the  absolute  quantity  of  oxygen  con- 
tained in  the  atmosphere  appears  very  great  when 
represented  by  numbers,  yet  it  is  not  inexhaustible. 
One  man  consumes  by  respiration  25  cubic  feet  of 
oxygen  in  24  hours ;  10  cwt.  of  charcoal  consume 
32,066  cubic  feet  of  oxygen  during  its  combustion ; 
and  a  small  town  like  Giessen  (with  about  7000 
inhabitants)  extracts  yearly  from  the  air,  by  the 
wood  employed  as  fuel,  more  than  551  millions  of 
cubic  feet  of  this  gas. 

When  we  consider  facts  such  as  these,  our  former 


QUANTITY  OF  OXYGEN  IN  THE  ATMOSPHERE.  41 


statement,  that  the  quantity  of  oxygen  in  the  atmo- 
sphere does  not  diminish  in  the  course  of  ages,*  — 
that  the  air  at  the  present  day,  for  example,  does 
not  contain  less  oxygen  than  that  found  in  jars 
buried  for  1800  years  in  Pompeii,  —  appears  quite 
incomprehensible,  unless  some  source  exists  whence 
the  oxygen  abstracted  is  replaced.  How  does  it 
happen,  then,  that  the  proportion  of  oxygen  in  the 
atmosphere  is  thus  invariable  ? 

The  answer  to  this  question  depends  upon  another; 
namely,  what  becomes  of  the  carbonic  acid,  which  is 
produced  during  the  respiration  of  animals,  and  by 
the  process  of  combustion  ?  A  cubic  foot  of  oxygen 
gas,  by  uniting  with  carbon  so  as  to  form  carbonic 
acid;  does  not  change  its  volume.  The  billions  of 
cubic  feet  of  oxygen  extracted  from  the  atmosphere, 
produce  the   same   number  of  billions  of  cubic  feet 

*  If  the  atmosphere  possessed,  in  its  whole  extent,  the  same  density 
as  it  does  on  the  surface  of  the  sea,  it  would  have  a  height  of  24,555 
Parisian  feet;  but  it  contains  the  vapor  of  water,  so  that  we  may  as- 
sume its  height  to  be  one  geographical  mile  ==  22,843  Parisian  feet.  Now 
the  radius  of  the  earth  is  equal  to  860  geographical  miles ;  hence  the 
Volume  of  the  atmosphere  =  9,307,500  cubic  miles. 

=  cube  of  210-4  miles. 
Volume  of  oxygen     .     .      =  1,954,578  cubic  miles. 

=  cube  of  125  miles. 
Volume  of  carbonic  acid      =  3,862-7  cubic  miles. 

=  cube  of  15'7  miles. 
The  maximum  of  the  carbonic  acid  contained  in  the  atmosphere  has 
not  here  been  adopted, but  the  mean,  which  is  equal  to  0-000415.  (L.)  The 
weight  of  carbon  which  presses  upon  each  square  inch  of  the  earth's 
surface  being  17*39  grains,  on  an  acre  of  land  will  be  7  tons. — (Johnston.) 
A  man  daily  consumes  45,000  cubic  inches  (Parisian).  A  man 
yearly  consumes  9505-2  cubic  feet.  100  million  men  yearly  consume 
9,505,200,000,000  cubic  feet. 

Hence  a  thousand  million  men  yearly  consume  0- 79745  cubic  miles 
of  oxygen.  But  the  air  is  rendered  incapable  of  supporting  the  pro- 
cess of  respiration,  when  the  quantity  of  its  oxygen  is  decreased  12 
per  cent. ;  so  that  a  thousand  million  men  would  make  the  air  unfit 
for  respiration  in  a  million  years.  The  consumption  of  oxygen  by 
animals,  and  by  the  process  of  combustion,  is  not  introduced  into  the 
calculation. 

When  the  air  returns  from  the  lungs,  the  carbonic  acid  gas  amounts, 
on  an  average,  to  55th  of  the  whole  ;  or  its  quantity  is  increased  one 
hundred  times.  —  (Johnston.)  A  full  grown  man  gives  off  from  his 
lungs,  in  the  course  of  a  year,  upwards  of  100  lbs.  of  carbon.  It  is 
estimated  by  Johnston,  that  at  least  one  third  of  the  carbon  of  the 
food  of  men  is  daily  returned  to  the  air, 

4  ♦ 


42  OF  THE  ASSIMILATION  OF  CARBON. 

of  carbonic  acid,  which  immediately  supply  its 
place. 

The  most  exact  and  most  recent  experiments  of 
De  Saussure,  made  in  every  season  for  a  space  of 
three  years,  have  shown,  that  the  air  contains  on  an 
average  0*000415  of  its  own  volume  of  carbonic  acid 
gas;  so  that,  allowing  for  the  inaccuracies  of  the 
experiments,  which  must  diminish  the  quantity  ob- 
tained, the  proportion  of  carbonic  acid  in  the  atmo- 
sphere may  be  regarded  as  nearly  equal  to  i^^ioth  part 
of  its  weight.  The  quantity  varies  according  to  the 
seasons ;  but  the  yearly  average  remains  continually 
the  same. 

We  have  no  reason  to  believe  that  this  proportion 
was  less  in  past  ages ;  and  nevertheless,  the  im- 
mense masses  of  carbonic  acid  which  annually  flow 
into  the  atmosphere  from  so  many  sources,  ought  per- 
ceptibly to  increase  its  quantity  from  year  to  year. 
But  we  find  that  all  earlier  observers  describe  its 
volume  as  from  one-half  to  ten  times  greater  than 
that  which  it  has  at  the  present  time  ;  so  that  we  can 
hence  at  most  conclude  that  it  has  diminished. 

It  is  quite  evident  that  the  quantities  of  carbonic 
acid  and  oxygen  in  the  atmosphere,  which  remain 
unchanged  by  lapse  of  time,  must  stand  in  some  fixed 
relation  to  one  another;  a  cause  must  exist  which 
prevents  the  increase  of  carbonic  acid  by  removing 
that  which  is  constantly  forming ;  and  there  must  be 
some  means  of  replacing  the  oxygen,  which  is  re- 
moved from  the  air  by  the  processes  of  combustion 
and  putrefaction,  as  w^ell  as  by  the  respiration  of 
animals. 

Both  these  causes  are  united  in  the  process  of 
vegetable  life. 

The  facts  which  we  have  stated  in  the  preceding 
pages  prove,  that  the  carbon  of  plants  must  be  de- 
rived exclusively  from  the  atmosphere.  Now,  carbon 
exists  in  the  atmosphere  only  in  the  form  of  carbonic 
acid,  and  therefore  in  a  state  of  combination  with 
oxygen. 


LIBERATION  OF  OXYGEN.  43 

It  has  been  already  mentioned  likewise,  that  car- 
bon and  the  elements  of  water  form  the  principal 
constituents  of  vegetables;  the  quantity  of  the  sub- 
stances which  do  not  possess  this  composition  being 
in  a  very  small  proportion.  Now,  the  relative  quan- 
tity of  oxygen  in  the  whole  mass  is  less  than  in  car- 
bonic acid;  for  the  latter  contains  tw^o  equivalents 
of  oxygen,  whilst  one  only  is  required  to  unite  with 
hydrogen  in  the  proportion  to  form  water.  The  veg- 
etable products  which  contain  oxygen  in  larger  pro- 
portion than  this,  are,  comparatively,  few  in  number; 
indeed  in  many  the  hydrogen  is  in  great  excess.  It 
is  obvious,  that  w^hen  the  hydrogen  of  water  is  as- 
similated by  a  plant,  the  oxygen  in  combination  with 
it  must  be  liberated,  and  will  afford  a  quantity  of 
this  element  sufficient  for  the  wants  of  the  plants. 
If  this  be  the  case,  the  oxygen  contained  in  the  car- 
bonic acid  is  quite  unnecessary  in  the  process  of 
vegetable  nutrition,  and  it  will  consequently  escape 
into  the  atmosphere  in  a  gaseous  form.  It  is  there- 
fore certain,  that  plants  must  possess  the  power  of 
decomposing  carbonic  acid,  since  they  appropriate 
its  carbon  for  their  own  use.  The  formation  of  their 
principal  component  substances  must  necessarily  be 
attended  with  the  separation  of  the  carbon  of  the 
carbonic  acid  from  the  oxygen,  which  must  be  re- 
turned to  the  atmosphere,  whilst  the  carbon  enters 
into  combination  with  water  or  its  elements.  The 
atmosphere  must  thus  receive  a  volume  of  oxygen 
for  every  volume  of  carbonic  acid  which  has  been 
decomposed. 

This  remarkable  property  of  plants  has  been  de- 
monstrated in  the  most  certain  manner,  and  it  is  in 
the  power  of  every  person  to  convince  himself  of  its 
existence.  The  leaves  and  other  green  parts  of  a 
plant  absorb  carbonic  acid,  and  emit  an  equal  volume 
of  oxygen.  They  possess  this  property  quite  inde- 
pendently of  the  plant ;  for  if,  after  being  separated 
from  the  stem,  they  are  placed  in  water  containing 
carbonic  acid,  and  exposed  in  that  condition  to  the 


44  OF  THE  ASSIMILATION  OF  CARBON. 

sun's  light,  the  carbonic  acid  is,  after  a  time,  found 
to  have  disappeared  entirely  from  the  water.  If  the 
experiment  is  conducted  under  a  glass  receiver  filled 
with  water,  the  oxygen  emitted  from  the  plant  may 
be  collected  and  examined.  When  no  more  oxygen 
gas  is  evolved,  it  is  a  sign  that  all  the  dissolved  car- 
bonic acid  is  decomposed ;  but  the  operation  recom- 
mences if  a  new  portion  of  it  is  added. 

Plants  do  not  emit  gas  when  placed  in  water  which 
either  is  free  from  carbonic  acid,  or  contains  an  al- 
kali that  protects  it  from  assimilation. 

These  observations  were  first  made  by  Priestley 
and  Sennebier.  The  excellent  experiments  of  De 
Saussure  have  further  shown,  that  plants  increase  in 
weight  during  the  decomposition  of  carbonic  acid 
and  separation  of  oxygen.  This  increase  in  weight 
is  greater  than  can  be  accounted  for  by  the  quantity 
of  carbon  assimilated ;  a  fact  which  confirms  the 
view,  that  the  elements  of  water  are  assimilated  at 
the  same  time. 

The  life  of  plants  is  closely  connected  with  that 
of  animals,  in  a  most  simple  manner,  and  for  a  wise 
and  sublime  purpose. 

The  presence  of  a  rich  and  luxuriant  vegetation 
may  be  conceived  without  the  concurrence  of  animal 
life,  but  the  existence  of  animals  is  undoubtedly  de- 
pendent upon  the  life  and  development  of  plants. 

Plants  not  only  afford  the  means  of  nutrition  for 
the  growth  and  continuance  of  animal  organization, 
but  they  likewise  furnish  that  which  is  essential  for 
the  support  of  the  important  vital  process  of  respira- 
tion ;  for  besides  separating  all  noxious  matters  from 
the  atmosphere,  they  are  an  inexhaustible  source  of 
pure  oxygen,  which  supplies  the  loss  which  the  air 
is  constantly  sustaining.  Animals  on  the  other  hand 
expire  carbon,  which  plants  inspire ;  and  thus  the 
composition  of  the  medium  in  which  both  exist,  name- 
ly, the  atmosphere,  is  maintained  constantly  un- 
changed. 

It  may  be  asked,  —  Is  the  quantity  of  carbonic  acid 


ITS  SOURCE  THE  ATMOSPHERE.  45 

in  the  atmosphere,  which  scarcely  amounts  to  ^th 
per  cent.,  sufficient  for  the  wants  of  the  whole  vege- 
tation on  the  surface  of  the  earth,  —  is  it  possible 
that  the  carbon  of  plants  has  its  origin  from  the  air 
alone  1  This  question  is  very  easily  answered.  It 
is  known,  that  a  column  of  air  of  2441  lbs.  weight 
rests  upon  every  square  Hessian  foot  (=0*567  square 
foot  English)  of  the  surface  of  the'^arth;  the  diame- 
ter of  the  earth  and  its  superficies  are  likewise  known, 
so  that  the  weight  of  the  atmosphere  can  be  calcu- 
lated with  the  greatest  exactness.  The  thousandth 
part  of  this  is  carbonic  acid,  which  contains  upwards 
of  27  per  cent,  carbon.  By  this  calculation  it 
can  be  shown,  that  the  atmosphere  contains  3306 
billion  lbs.  of  carbon ;  a  quantity  which  amounts  to 
more  than  the  weight  of  all  the  plants,  and  of  all  the 
strata  of  mineral  and  brown  coal,  which  exist  upon 
the  earth.  This  carbon  is,  therefore,  more  than  ade- 
quate to  all  the  purposes  for  which  it  is  required. 
The  quantity  of  carbon  contained  in  sea-water  is 
proportionally  still  greater. 

If,  for  the  sake  of  argument,  we  suppose  the  su- 
perficies of  the  leaves  and  other  green  parts  of  plants, 
by  which  the  absorption  of  carbonic  acid  is  effected, 
to  be  double  that  of  the  soil  upon  which  they  grow, 
a  supposition  which  is  much  under  the  truth  in  the 
case  of  woods,  meadows,  and  corn-fields ;  and  if  we 
further  suppose  that  carbonic  acid  equal  to  0*00067 
of  the  volume  of  the  air,  or  i^th  of  its  weight, 
is  abstracted  from  it  during  every  second  of  time, 
for  eight  hours  daily,  by  a  field  of  53,820  square  feet 
(  =  2  Hessian  acres);  then  those  leaves  would  re- 
ceive 1102  lbs.  of  carbon  in  200  days.* 

*  The  quantity  of  carbonic  acid  which  can  be  extracted  from  the  air 
in  a  given  time,  is  shown  by  the  following  calculation.  During  the 
white- washing  of  a  small  chamber,  the  superficies  of  the  walls  and  roof 
of  which  we  will  suppose  to  be  105  square  metres,  and  which  receives 
six  coats  of  lime  in  four  days,  carbonic  acid  is  abstracted  from  the  air, 
and  the  lime  is  consequently  converted,  on  the  surface,  into  a  carbon- 
ate. It  has  been  accurately  determined  that  one  square  decimetre  re- 
ceives in  this  way,  a  coating  of  carbonate  of  lime  which  weighs  0732 
grammes.    Upon  the  105  square  metres  already  mentioned  there  must 


46  OF  THE  ASSIMILATION  OF  CARBON. 

But  it  is  inconceivable,  that  the  functions  of  the 
organs-  of  a  plant  can  cease  for  any  one  moment 
during  its  life.  The  roots  and  other  parts  of  it, 
which  possess  the  same  power,  absorb  constantly 
water  and  carbonic  acid.  This  power  is  independ- 
ent of  solar  light.  During  the  day,  when  plants  are 
in  the  shade,  and  during  the  night,  carbonic  acid  is 
accumulated  in  all  parts  of  their  structure ;  and  the 
assimilation  of  the  carbon  and  the  exhalation  of 
oxygen  commence  from  the  instant  that  the  rays  of 
the  sun  strike  them.  As  soon  as  a  young  plant 
breaks  through  the  surface  of  the  ground,  it  begins 
to  acquire  color  from  the  top  downwards ;  and  the 
true  formation  of  woody  tissue  commences  at  the 
same  time.* 

The  proper,  constant,  and  inexhaustible  sources 
of  oxygen  gas  are  the  tropics  and  warm  climates, 
where  a  sky,  seldom  clouded,  permits  the  glowing 
rays  of  the  sun  to  shine  upon  an  immeasurably 
luxuriant  vegetation.  The  temperate  and  cold  zones, 
where  artificial  warmth  must  replace  deficient  heat 
of  the  sun,  produce,  on  the  contrary,  carbonic  acid 
in  superabundance,  which  is  expended  in  the  nutri- 
tion of  the  tropical  plants.  The  same  stream  of 
air,  which  moves  by  the  revolution  of  the  earth  from 
the  equator  to  the  poles,  brings  to  us,  in  its  passage 
from  the  equator,  the  oxygen  generated  there,  and 
carries  away  the  carbonic  acid  formed  during  our 
winter. 


accordingly  be  formed  7686  grammes  of  carbonate  of  lime,  which  con- 
tain 4325-6  grammes  of  carbonic  acid.  The  weight  of  one  cubic  deci- 
metre of  carbonic  acid  being  calculated  at  two  grammes,  (more  accu- 
rately 1-97978,)  the  above-mentioned  surface  must  absorb  in  four  days 
2-163  cubic  metres  of  carbonic  acid.  2500  square  metres  (one  Hessian 
acre)  would  absorb,  under  a  similar  treatment,  51^  cubic  metres  =  1818 
cubic  feet  of  carbonic  acid  in  four  days.  In  200  days  it  would  absorb 
2575  cubic  metres  =  904,401  cubic  feet,  which  contain  11,353  lbs.  of 
carbonic  acid,  of  which  3304  lbs.  are  carbon,  a  quantity  three  times  as 
great  as  that  which  is  assimilated  by  the  leaves  and  roots  growing  upon 
the  same  space.  —  L. 

*  Plants  that  grow  in  the  dark,  are  well  known  to  be  colorless.  This 
is  seen  in  the  blanching  of  celery  (etiolation),  the  earth  is  heaped 
around  the  stalks  to  exclude  the  light. 


ITS  SOURCE  THE  ATMOSPHERE.  47 

The  experiments  of  De  Saussure  have  proved, 
that  the  upper  strata  of  the  air  contain  more  car- 
bonic acid  than  the  lower,  which  are  in  contact  with 
plants ;  and  that  the  quantity  is  greater  by  night 
than  by  day,  when  it  undergoes  decomposition. 

Plants  thus  improve  the  air,  by  the  removal  of 
carbonic  acid,  and  by  the  renewal  of  oxygen,  which 
is  immediately  applied  to  the  use  of  man  and  animals. 
The  horizontal  currents  of  the  atmosphere  bring 
with  them  as  much  as  they  carry  away,  and  the  in- 
terchange of  air  between  the  upper  and  lower  strata, 
which  their  difference  of  temperature  causes,  is 
extremely  trifling  when  compared  with  the  horizon- 
tal movements  of  the  winds.  Thus  vegetable  culture 
heightens  the  healthy  state  of  a  country,  and  a 
previously  healthy  country  would  be  rendered  quite 
uninhabitable  by  the  cessation  of  all  cultivation. 

The  various  layers  of  wood  and  mineral^coal,  as 
well  as  peat,  form  the  remains  of  a  primeval  vegeta- 
tion.     The  carbon   which  they  contain  must  have 
been  originally  in  the  atmosphere  as  carbonic  acid, 
in  which  form  it  was  assimilated  by  the  plants  which 
constitute   these  formations.     It  follows  from   this, 
that  the  atmosphere  must  be  richer  in  oxygen  at  the 
present  time   than  in  former  periods  of  the   earth's 
history.     The   increase  must  be  exactly  proportional 
to  the   quantity  of  carbon   and  hydrogen  contained 
in  these  carboniferous   deposits.     Thus,  during  the 
formation  of  353  cubic  feet  of  Newcastle  splint-coal, 
the  atmosphere  must  have  received  643  cubic  feet 
of  oxygen  produced  from  the   carbonic   acid   assim- 
ilated,  and   also    158    cubic   feet   of  the    same   gas 
resulting    from    the    decomposition    of    water.      In 
former  ages,  therefore,  the   atmosphere    must  have 
contained  less  oxygen,  but  a  much  larger  proportion 
of  carbonic  acid,  than  it  does  at   the   present  time, 
a  circumstance  which  accounts  for  the  richness  and 
luxuriance  of  the  earlier  vegetation. 

But  a  certain   period  must  have  arrived  in  which 
the  quantity  of  carbonic   acid  contained  in  the   air 


48  OF  THE  ASSIMILATION  OF  CARBON. 

experienced  neither  increase  nor  diminution  in  any- 
appreciable  quantity.  For  if  it  received  an  addi- 
tional quantity  to  its  usual  proportion,  an  increased 
vegetation  would  be  the  natural  consequence,  and 
the  excess  would  thus  be  speedily  removed.  And, 
on  the  other  hand,  if  the  gas  was  less  than  the 
normal  quantity,  the  progress  of  vegetation  would 
be  retarded,  and  the  proportion  would  soon  attain 
its  proper  standard. 

The  most  important  function  in  the  life  of  plants,, 
or,  in  other  words,  in  their  assimilation  of  carbon, 
is  the  separation,  we  might  almost  say,  the  genera- 
tion of  oxygen.  No  matter  can  be  considered  as 
nutritious,  or  as  necessary  to  the  growth  of  plants, 
which  possesses  a  composition  either  similar  to  or 
identical  with  theirs,  and  the  assimilation  of  which, 
therefore,  could  take  place  without  exercising  this 
function.  The  reverse  is  the  case  in  the  nutrition 
of  animals.  Hence  such  substances  as  sugar,  starch, 
and  gum,  which  are  themselves  products  of  plants, 
cannot  be  adapted  for  assimilation.  And  this  is 
rendered  certain  by  the  experiments  of  vegetable 
physiologists,  who  have  shown  that  aqueous  solutions 
of  these  bodies  are  imbibed  by  the  roots  of  plants, 
and  carried  to  all  parts  of  their  structure,  but  are 
not  assimilated ;  they  cannot  therefore  be  employed 
in  their  nutrition.  We  could  scarcely  conceive  a 
form  more  convenient  for  assimilation  than  that  of 
gum,  starch,  and  sugar,  for  they  all  contain  the 
elements  of  woody  fibre,  and  nearly  in  the  same  pro- 
portions. 

In  the  second  part  of  the  work  we  shall  adduce 
satisfactory  proofs  that  decayed  woody  fibre  {humus) 
contains  carbon  and  the  elements  of  water,  without 
an  excess  of  oxygen ;  its  composition  differing  from 
that  of  woody  fibre  in  its  being  richer  in  carbon. 

Misled  by  this  simplicity  in  its  constitution,  phy- 
siologists found  no  difficulty  in  discovering  the  mode 
of  the  formation  of  woody  fibre ;  for  they  say,*  hu- 

*  Meyen,  PJlanzenphysiologief  II.  S.  141. 


I 


SEPARATION  OF  OXYGEN.  49 

mus  has  only  to  enter  into  combination  with  water, 
in  order  to  effect  the  formation  of  woody  fibre,  and 
other  substances  similarly  composed,  such  as  sugar, 
starch,  and  gum.  But  they  forget,  that  their  own 
experiments  have  sufficiently  demonstrated  the  inapt- 
itude of  these  substances  for  assimilation. 

All  the  erroneous  opinions  concerning  the  modus 
operandi  of  humus  have  their  origin  in  the  false 
notions  entertained  respecting  the  most  important 
vital  functions  of  plants  ;  analogy,  that  fertile  source 
of  error,  having,  unfortunately,  led  to  the  very  unapt 
comparison  of  the  vital  functions  of  plants  with 
those  of  animals. 

Substances,  such  as  sugar,  starch,  &c»,  which  con- 
tain carbon  and  the  elements  of  water,  are  products 
of  the  life  of  plants  which  live  only  whilst  they 
generate  them.  The  same  may  be  said  of  humus, 
for  it  can  be  formed  in  plants  like  the  former  sub- 
stances. Smithson,  Jameson,  and  Thomson,  found 
that  the  black  excretions  of  unhealthy  elms,  oaks, 
and  horse-chesnuts,  consisted  of  humic  acid  in  com- 
bination with  alkalies.  Berzelius  detected  similar 
products  in  the  bark  of  most  trees.  Now,  can  it  be 
supposed  that  the  diseased  organs  of  a  plant  possess 
the  power  of  generating  the  matter  to  which  its 
sustenance  and  vigor  are  ascribed  ? 

How  does  it  happen,  it  may  be  asked,  that  the 
absorption  of  carbon  from  the  atmosphere  by  plants 
is  doubted  by  all  botanists  and  vegetable  physiolo- 
gists, and  that  by  the  greater  number  the  purification 
of  the  air  by  means  of  them  is  wholly  denied  ? 

The  action  of  plants  on  the  air  in  the  absence  of 
light,  that  is  during  night,  has  been  much  miscon- 
ceived by  botanists,  and  from  this  we  may  trace 
most  of  the  errors  which  abound  in  the  greater  part 
of  their  writings.  The  experiments  of  Ingenhouss 
were  in  a  great  degree  the  cause  of  this  uncertainty 
of  opinion  regarding  the  influence  of  plants  in  puri- 
fying  the  air.  His  observation,  that  green  plants 
emit  carbonic  acid  in  the  dark,  led  De  Saussure  and 

5 


60  OF  THE  ASSIMILATION  OF  CARBON. 

Grischow  to  new  investigations,  by  which  they 
ascertained,  that  under  such  conditions  plants  do 
really  absorb  oxygen  and  emit  carbonic  acid ;  but 
that  the  whole  volume  of  air  undergoes  diminution 
at  the  same  time.  From  the  latter  fact  it  follows, 
that  the  quantity  of  oxygen  gas  absorbed  is  greater 
than  the  volume  of  carbonic  acid  separated ;  for,  if 
this  were  not  the  case,  no  diminution  could  occur. 
These  facts  cannot  be  doubted,  but  the  views  based 
on  them  have  been  so  false,  that  nothing,  except  the 
total  want  of  observation  and  the  utmost  ignorance 
of  the  chemical  relations  of  plants  to  the  atmo- 
sphere, can  account  for  their  adoption. 

It  is  known  that  nitrogen,  hydrogen,  and  a  num- 
ber of  other  gases,  exercise  a  peculiar,  and  in  gen- 
eral an  injurious  influence  upon  living  plants.  Is  it, 
then,  probable,  that  oxygen,  one  of  the  most  ener- 
getic agents  in  nature,  should  remain  without  influ- 
ence on  plants  when  one  of  their  peculiar  processes 
of  assimilation  has  ceased  ? 

It  is  true  that  the  decomposition  of  carbonic  acid 
is  arrested  by  absence  of  light.  But  then,  namely, 
at  night,  a  true  chemical  process  commences,  in 
consequence  of  the  action  of  the  oxygen  in  the  air, 
upon  the  organic  substances  composing  the  leaves, 
blossoms,  and  fruit.  This  process  is  not  at  all  con- 
nected with  the  life  of  the  vegetable  organism, 
because  it  goes  on  in  a  dead  plant  exactly  as  in  a 
living  one. 

The  substances  composing  the  leaves  of  different 
plants  being  known,  it  is  a  matter  of  the  greatest 
ease  and  certainty  to  calculate  which  of  them,  dur- 
ing life,  should  absorb  most  oxygen  by  chemical 
action  when  the  influence  of  light  is  withdrawn. 

The  leaves  and  green  parts  of  all  plants  contain- 
ing volatile  oils  or  volatile  constituents  in  general, 
which  change  into  resin  by  the  absorption  of  oxygen, 
should  absorb  more  than  other  parts  which  are  free 
from  such  substances.  Those  leaves,  also,  which 
contain  either  the  constituents  of  nut-galls,  or  com- 


INFLUENCE  OF  THE  SHADE  ON  PLANTS.         51 

pounds  in  which  nitrogen  is  present,  ought  to  absorb 
more  oxygen  than  those  which  do  not  contain  such 
matters.  The  correctness  of  these  inferences  has 
been  distinctly  proved  by  the  observations  of  De 
Saussure ;  for,  whilst  the  tasteless  leaves  of  the 
Agave  americana  absorb  only  0*3  of  their  volume  of 
oxygen  in  the  dark,  during  24  hours,  the  leaves  of 
the  Pinus  Abies,  which  contain  volatile  and  resinous 
oils,  absorb  10  times,  those  of  the  Quercus  Rohur 
containing  tannic  acid  14  times,  and  the  balmy  leaves 
of  the  Populus  alba  21  times  that  quantity.  This 
chemical  action  is  shown  very  plainly,  also,  in  the 
leaves  of  the  Cotyledon  calycinum,  the  Cacalia 
JicoideSj  and  others ;  for  they  are  sour  like  sorrel  in 
the  morning,  tasteless  at  noon,  and  bitter  in  the 
evening.  The  formation  of  acids  is  effected  during 
the  night  by  a  true  process  of  oxidation :  these  are 
deprived  of  their  acid  properties  during  the  day  and 
evening,  and  are  changed  by  separation  of  a  part  of 
their  oxygen  into  compounds  containing  oxygen  and 
hydrogen,  either  in  the  same  proportions  as  in  water, 
or  even  with  an  excess  of  hydrogen,  which  is  the 
composition  of  all  tasteless  and  bitter  substances. 

Indeed  the  quantity  of  oxygen  absorbed  could  be 
estimated  pretty  nearly  by  the  different  periods 
which  the  green  leaves  of  plants  require  to  undergo 
alteration  in  color,  by  the  influence  of  the  atmosphere. 
Those  which  continue  longest  green  will  abstract 
less  oxygen  from  the  air  in  an  equal  space  of  time, 
than  those,  the  constituent  parts  of  which  suffer  a 
more  rapid  change.  It  is  found,  for  example,  that 
the  leaves  of  the  Ilex  aquifolium,  distinguished  by 
the  durability  of  their  color,  absorb  only  0*86  of 
their  volume  of  oxygen  gas  in  the  same  time  that 
the  leaves  of  the  poplar  absorb  8,  and  those  of  the 
beech  9J  times  their  volume ;  both  the  beech  and 
poplar  being  remarkable  for  the  rapidity  and  ease 
with  which  the  color  of  their  leaves  changes. 

When  the  green  leaves  of  the  poplar,  the  beech, 
the  oak,  or  the  holly,  are   dried  under  the  air-pump, 


52  OF  THE  ASSIMILATION  OF  CARBON. 

with  exclusion  of  light,  then  moistened  with  water, 
and  placed  under  a  glass  globe  filled  with  oxygen, 
they  are  found  to  absorb  that  gas  in  proportion  as 
they  change  in  color.  The  chemical  nature  of  this 
process  is  thus  completely  established.  The  diminu- 
tion of  the  gas  which  occurs  can  only  be  owing  to 
the  union  of  a  large  proportion  of  oxygen  with  those 
substances  which  are  already  in  the  state  of  oxides, 
or  to  the  oxidation  of  the  hydrogen  in  those  vege- 
table compounds  which  contain  it  in  excess.  The 
fallen  brown  or  yellow  leaves  of  the  oak  contain  no 
longer  tannin,  and  those  of  the  poplar  no  balsamic 
constituents. 

The  property  which  green  leaves  possess  of  ab- 
sorbing oxygen  belongs  also  to  fresh  wood,  whether 
taken  from  a  twig  or  from  the  interior  of  the  trunk 
of  a  tree.  When  fine  chips  of  such  wood  are  placed 
in  a  moist  condition  under  a  jar  filled  with  oxygen, 
the  gas  is  seen  to  diminish  in  volume.  But  w^ood, 
dried  by  exposure  to  the  atmosphere  and  then  moist- 
ened, converts  the  oxygen  into  carbonic  acid,  with- 
out change  of  volume  ;  fresh  wood,  therefore,  absorbs 
most  oxygen. 

MM.  Petersen  and  Schodler  have  shown,  by  the 
careful  elementary  analysis  of  24  different  kinds  of 
wood,  that  they  contain  carbon  and  the  elements  of 
water,  with  the  addition  of  a  certain  quantity  of 
hydrogen.  Oak  wood,  recently  taken  from  the  tree, 
and  dried  at  100^  C.  (212^  F.),  contains  49-432 
carbon,  6*069  hydrogen,  and  44-499  oxygen. 

The  proportion  of  hydrogen  which  is  necessary  to 
combine  with  44-498  oxygen  in  order  to  form  water, 
is  I  of  this  quantity,  namely,  5-56 ;  it  is  evident, 
therefore,  that  oak  wood  contains  ^^  more  hydrogen 
than  corresponds  to  this  proportion.  In  Finns 
Larix,  P.  Abies,  and  P.  picea,  the  excess  of  hydro- 
gen amounts  to  ^,  and  in  Tilia  europcea  to  §.  The 
quantity  of  hydrogen  stands  in  some  relation  to  the 
specific  weight  of  the  wood;  the  lighter  kinds  of 
wood  contain  more  of  it  than  the  heavier.     In  ebony 


EVOLUTION  OF  CARBONIC  ACID  DURING  THE  NIGHT.  53 

wood  (^Diospyros  Ehenum)  the  oxygen  and  hydrogen 
are  in  exactly  the  same  proportion  as  in  water. 

The  difference  between  the  composition  of  the 
varieties  of  wood,  and  that  of  simple  woody  fibre, 
depends,  unquestionably,  upon  the  presence  of  con- 
stituents, in  part  soluble,  and  in  part  insoluble,  such 
as  resin  and  other  matters,  which  contain  a  large 
proportion  of  hydrogen :  the  hydrogen  of  such  sub- 
stances being  in  the  analysis  of  the  various  woods 
superadded  to  that  of  the  true  woody  fibre. 

It  has  previously  been  mentioned  that  mouldering 
oak  wood  contains  carbon  and  the  elements  of  water, 
without  any  excess  of  hydrogen.  But  the  propor- 
tions of  its  constituents  must  necessarily  have  been 
different,  if  the  volume  of  the  air  had  not  changed 
during  its  decay,  because  the  proportion  of  hydrogen 
in  those  component  substances  of  the  wood  which 
contained  it  in  excess  is  here  diminished,  and  this 
diminution  could  only  be  effected  by  an  absorption 
of  oxygen,  and  consequent  formation  of  water. 

Most  vegetable  physiologists  have  connected  the 
emission  of  carbonic  acid  during  the  night  with  the 
absorption  of  oxygen  from  the  atmosphere,  and  have 
considered  these  actions  as  a  true  process  of  respi- 
ration in  plants,  similar  to  that  of  animals,  and  like 
it,  having  for  its  result  the  separation  of  carbon 
from  some  of  their  constituents.  This  opinion  has 
a  very  weak  and  unstable  foundation. 

The  carbonic  acid,  which  has  been  absorbed  by 
the  leaves  and  by  the  roots,  together  with  water, 
ceases  to  be  decomposed  on  the  departure  of  day- 
light;  it  is  dissolved  in  the  juices  which  pervade 
all  parts  of  the  plant,  and  escapes  every  moment 
through  the  leaves  in  quantity  corresponding  to  that 
of  the  water  which  evaporates. 

A  soil  in  which  plants  vegetate  vigorously,  con- 
tains a  certain  quantity  of  moisture  which  is  indis- 
pensably necessary  to  their  existence.  Carbonic 
acid,  likewise,  is  always  present  in  such  a  soil, 
whether  it  has  been   abstracted  from  the  air  or  has 


54  OF  THE  ASSIMILATION  OF  CARBON. 

been  generated  by  the  decay  of  vegetable  matter. 
Rain  and  well  water,  and  also  that  from  other 
sources,  invariably  contains  carbonic  acid.  —  Plants 
during  their  life  constantly  possess  the  power  of 
absorbing  by  their  roots  moisture,  and,  along  with 
it,  air  and  carbonic  acid.  Is  it,  therefore,  surprising 
that  the  carbonic  acid  should  be  returned  unchanged 
to  the  atmosphere,  along  with  water,  when  light 
(the  cause  of  the  fixation  of  its  carbon)  is  absent? 

Neither  this  emission  of  carbonic  acid  nor  the- 
absorption  of  oxygen  has  any  connexion  with  the 
process  of  assimilation ;  nor  have  they  the  slightest 
relation  to  one  another;  the  one  is  a  purely  me- 
chanical, the  other  a  purely  chemical  process.  A 
cotton  wick,  inclosed  in  a  lamp,  which  contains  a 
liquid  saturated  with  carbonic  acid,  acts  exactly  in 
the  same  manner  as  a  living  plant  in  the  night. 
Water  and  carbonic  acid  are  sucked  up  by  capillary 
attraction,  and  both  evaporate  from  the  exterior  part 
of  the  wick. 

Plants  which  live  in  a  soil  containing  humus  exhale 
much  more  carbonic  acid  during  the  night  than  those 
which  grow  in  dry  situations ;  they  also  yield  more 
in  rainy  than  in  dry  weather.  These  facts  point  out 
to  us  the  cause  of  the  numerous  contradictory 
observations,  which  have  been  made  with  respect  to 
the  change  impressed  upon  the  air  by  living  plants, 
both  in  darkness  and  in  common  daylight,  but 
which  are  unworthy  of  consideration,  as  they  do  not 
assist  in  the  solution  of  the  main  question. 

There  are  other  facts  which  prove  in  a  decisive 
manner  that  plants  yield  more  oxygen  to  the  atmo- 
sphere than  they  extract  from  it ;  these  proofs, 
however,  are  to  be  drawn  with  certainty  only  from 
plants  which  live  under  water. 

When  pools  and  ditches,  the  bottoms  of  which 
are  covered  with  growing  plants,  freeze  upon  their 
surface  in  winter,  so  that  the  water  is  completely 
excluded  from  the  atmosphere  by  a  clear  stratum  of 
ice,  small  bubbles  of  gas  are  observed  to  escape,  con- 


NEGLECT  OF  CHEMISTRY  BY  BOTANISTS.  55 

tinually,  during  the  day,  from  the  points  of  the  leaves 
and  twigs.  These  bubbles  are  seen  most  distinctly 
when  the  rays  of  the  sun  fall  upon  the  ice ;  they  are 
very  small  at  first,  but  collect  under  the  ice  and  form 
larger  bubbles.  They  consist  of  pure  oxygen  gas. 
Neither  during  the  night,  nor  during  the  day  when 
the  sun  does  not  shine,  are  they  observed  to  diminish 
in  quantity.  The  source  of  this  oxygen  is  the  car- 
bonic acid  dissolved  in  the  water,  which  is  absorbed 
by  the  plants,  but  is  again  supplied  to  the  water,  by 
the  decay  of  vegetable  substances  contained  in  the 
soil.  If  these  plants  absorb  oxygen  during  the  night, 
it  can  be  in  no  greater  quantity  than  that  which  the 
surrounding  water  holds  in  solution,  for  the  gas, 
which  has  been  exhaled,  is  not  again  absorbed.  The 
action  of  water-plants  cannot  be  supposed  to  form 
an  exception  to  a  great  law  of  nature,  and  the  less 
so,  as  the  different  action  of  aerial  plants  upon  the 
atmosphere  is  very  easily  explained. 

The  opinion  is  not  new,  that  the  carbonic  acid  of 
the  air  serves  for  the  nutriment  of  plants,  and  that 
its  carbon  is  assimilated  by  them ;  it  has  been  ad- 
mitted, defended,  and  argued  for,  by  the  soundest 
and  most  intelligent  natural  philosophers,  namely,  by 
Priestley,  Sennebier,  De  Saussure,  and  even  by  In- 
genhouss  himself.  There  scarcely  exists  a  theory 
in  natural  science,  in  favor  of  which  there  are  more 
clear  and  decisive  arguments.  How,  then,  are  we 
to  account  for  its  not  being  received  in  its  full  extent 
by  most  other  physiologists,  for  its  being  even  dis- 
puted by  many,  and  considered  by  a  few  as  quite 
refuted  ? 

All  this  is  due  to  two  causes,  which  we  shall  now 
consider. 

One  is,  that  in  botany  the  talent  and  labor  of  in- 
quirers has  been  "wholly  spent  in  the  examination  of 
form  and  structure :  chemistry  and  physics  have  not 
been  allowed  to  sit  in  council  upon  the  explanation 
of  the  most  simple  processes  ;  their  experience  and 
their  laws  have  not  been  employed,  though  the  most 


56  OF  THE  ASSIMILATION  OF  CARBON. 

powerful  means  of  help  in  the  acquirement  of  true 
knowledge.  They  have  not  been  used,  because  their 
study  has  been  neglected. 

All  discoveries  in  physics  and  in  chemistry,  all 
explanations  of  chemists,  must  remain  without  fruit 
and  useless,  because,  even  to  the  great  leaders  in 
physiology,  carbonic  acid,  ammonia,  acids,  and  bases, 
are  sounds  without  meaning,  words  without  sense, 
terms  of  an  unknown  language,  which  awaken  no 
thoughts  and  no  associations.  They  treat  these 
sciences  like  the  vulgar,  who  despise  a  foreign  lite- 
rature in  exact  proportion  to  their  ignorance  of  it ; 
since  even  when  they  have  had  some  acquaintance 
with  them,  they  have  not  understood  their  spirit  and 
application. 

Physiologists  reject  the  aid  of  chemistry  in  their 
inquiry  into  the  secrets  of  vitality,  although  it  alone 
could  guide  them  in  the  true  path ;  they  reject  chem- 
istry, because  in  its  pursuit  of  knowledge  it  destroys 
the  subjects  of  its  investigation ;  but  they  forget 
that  the  knife  of  the  anatomist  must  dismember  the 
body,  and  destroy  its  organs,  if  an  account  is  to  be 
given  of  their  form,  structure,  and  functions. 

When  pure  potato  starch  is  dissolved  in  nitric 
acid,  a  ring  of  the  finest  wax  remains.  What  can 
be  opposed  to  the  conclusion  of  the  chemist,  that 
each  grain  of  starch  consists  of  concentric  layers  of 
wax  and  amylin,  which  thus  mutually  protect  each 
other  against  the  action  of  water  and  ether  ?  Can 
results  of  this  kind,  which  illustrate  so  completely 
both  the  nature  and  properties  of  bodies,  be  attained 
by  the  microscope  ?  Is  it  possible  to  make  the  glu- 
ten in  a  piece  of  bread  visible  in  all  its  connexions 
and  ramifications?  It  is  impossible  by  means  of  in- 
struments ;  but  if  the  piece  of  bread  is  placed  in  a 
lukewarm  decoction  of  malt,  the  starch,  and  the  sub- 
stance  called   dextrine,*  are   seen  to   dissolve  like 

*  According  to  Raspail,  starch  consists  of  vesicles  inclosing  within 
them  a  fluid  resembling  gum.  Starch  may  be  put  in  cold  water  with- 
out being  dissolved ;  but;  when  placed  in  hot  water,  these  spherules 


OBJECT  OF  EXPERIMENTS  IN  PHYSIOLOGY.  57 

sugar  in  water,  and,  at  last,  nothing  remains  except 
the  gluten,  in  the  form  of  a  spongy  mass,  the  minute 
pores  of  which  can  be  seen  only  by  a  microscope. 

Chemistry  offers  innumerable  resources  of  this  kind 
which  are  of  the  greatest  use  in  an  inquiry  into  the 
nature  of  the  organs  of  plants  ;  but  they  are  not  used, 
because  the  need  of  them  is  not  felt.  The  most  im- 
portant organs  of  animals  and  their  functions  are 
known,  although  they  may  not  be  visible  to  the 
naked  eye.  But  in  vegetable  physiology,  a  leaf  is  in 
every  case  regarded  merely  as  a  leaf,  notwithstand- 
ing that  leaves  generating  oil  of  turpentine  or  oil  of 
lemons  must  possess  a  different  nature  from  those 
in  which  oxalic  acid  is  formed.  Vitality,  in  its  pe- 
culiar operations,  makes  use  of  a  special  apparatus 
for  each  function  of  an  organ.  A  rose-twig  engraft- 
ed upon  a  lemon-tree  does  not  bring  forth  lemons, 
but  roses.  Vegetable  physiologists  in  the  study  of 
their  science  have  not  directed  their  attention  to  that 
part  of  it  which  is  most  worthy  of  investigation. 

The  second  cause  of  the  incredulity  with  which 
physiologists  view  the  theory  of  the  nutrition  of 
plants  by  the  carbonic  acid  of  the  atmosphere  is, 
that  the  art  of  experimenting  is  not  known  in  physi- 
ology, it  being  an  art  which  can  be  learned  accurate- 
ly only  in  the  chemical  laboratory.  Nature  speaks 
to  us  in  a  peculiar  language,  in  the  language  of  phe- 
nomena ;  she  answers  at  all  times  the  questions  which 
are  put  to  her  ;  and  such  questions  are  experiments. 
An  experiment  is  the  expression  of  a  thought :  we 
are  near  the  truth  when  the  phenomenon  elicited  by 
the  experiment   corresponds   to  the  thought ;  while 

burst,  and  allow  the  escape  of  the  liquid.  This  liquid  is  the  dextrine 
of  Biot,  so  called  because  it  possesses  the  property  of  turning  the  plane 
of  the  polarization  of  light  to  the  right  hand.  It  is  white,  insipid,  trans- 
parent in  thin  flakes  and  gummy.  At  280°  F.  it  becomes  brown  and 
acquires  the  flavor  of  toasted  bread.  It  is  much  employed  by  the  French 
pastry  cooks  and  confectioners ;  being  reduced  to  powder  it  may  be  in- 
troduced into  all  kinds  of  pastries,  bread,  chocolate,  &c.  For  its  prep- 
aration, &c.,  see  Ure's  Dictionary  of  Arts  and  Manufactures  fa.nd  Web- 
ster's Chemistry  J  510. 


58  OF  THE  ASSIMILATION  OF  CARBON. 

the  opposite  result  shows  that  the  question  was  false- 
ly stated,  and  that  the  conception  was  erroneous. 

The  critical  repetition  of  another's  experiments 
must  be  viewed  as  a  criticism  of  his  opinions ;  if  the 
result  of  the  criticism  be  merely  negative,  if  it  do  not 
suggest  more  correct  ideas  in  the  place  of  those 
which  it  is  intended  to  refute,  it  should  be  disre- 
garded ;  because  the  worse  experimenter  the  critic 
is,  the  greater  will  be  the  discrepancy  between  the 
results  he  obtains  and  the  views  proposed  by  the 
other. 

It  is  too  much  forgotten  by  physiologists,  that  their 
duty  really  is  not  to  refute  the  experiments  of  others, 
nor  to  show  that  they  are  erroneous,  but  to  discover 
truth,  and  that  alone.  It  is  startling,  when  we  re- 
flect that  all  the  time  and  energy^  of  a  multitude  of 
persons  of  genius,  talent,  and  knowledge,  are  ex- 
pended in  endeavors  to  demonstrate  each  other's 
errors. 

The  question  whether  carbonic  acid  is  the  food  of 
plants  or  not  has  been  made  the  subject  of  experi- 
ments with  perfect  zeal  and  good  faith ;  the  results 
have  been  opposed  to  that  view.  But  how  was  the 
inquiry  instituted  ? 

The  seeds  of  balsamines,  beans,  cresses,  and 
gourds,  were  sown  in  pure  Carrara  marble,  and 
sprinkled  with  water  containing  carbonic  acid.  The 
seeds  sprang,  but  the  plants  did  not  attain  to  the 
development  of  the  third  small  leaf.  In  other  cases, 
they  allowed  the  water  to  penetrate  the  marble  from 
below,  yet,  in  spite  of  this,  they  died.  It  is  worthy 
of  observation,  that  they  lived  longer  with  pure  dis- 
tilled water  than  with  that  impregnated  with  carbon- 
ic acid ;  but  still,  in  this  case  also,  they  eventually 
perished.  Other  experimenters  sowed  seeds  of  plants 
in  flowers  of  sulphur  and  sulphate  of  barytes,  and 
tried  to  nourish  them  with  carbonic  acid,  but  without 
success. 

Such  experiments  have  been  considered  as  positive 
proofs,  that  carbonic  acid  will  not  nourish  plants ; 


CONDITIONS  ESSENTIAL  TO  NUTRITION.  59 

but  the  manner  in  which  they  were  instituted  is  op- 
posed to  all  rules  of  philosophical  inquiry,  and  to  all 
the  laws  of  chemistry. 

Many  conditions  are  necessary  for  the  life  of  plants; 
those  of  each  genus  require  special  conditions ;  and 
should  but  one  of  these  be  wanting,  although  the 
rest  be  supplied,  the  plants  will  not  be  brought  to 
maturity.  The  organs  of  a  plant,  as  well  as  those 
of  an  animal,  contain  substances  of  the  most  differ- 
ent kinds  ;  some  are  formed  solely  of  carbon  and  the 
elements  of  water,  others  contain  nitrogen,  and  in 
all  plants  we  find  metallic  oxides  in  the  state  of  salts. 
The  food  which  can  serve  for  the  production  of  all 
the  organs  of  a  plant,  must  necessarily  contain  all  its 
elements.  These  most  essential  of  all  the  chemical 
qualities  of  nutriment  may  be  united  in  one  substance, 
or  they  may  exist  separately  in  several ;  in  which 
case,  the  one  contains  what  is  wanting  in  the  other. 
Dogs  die  although  fed  with  jelly,  a  substance  which 
contains  nitrogen  ;  they  cannot  live  upon  white  bread, 
sugar,  or  starch,  if  these  are  given  as  food,  to  the 
exclusion  of, all  other  substances.  Can  it  be  con- 
cluded from  this,  that  these  substances  contain  no 
elements  suited  for  assimilation  ?     Certainly  not. 

Vitality  is  the  power  which  each  organ  possesses 
of  constantly  reproducing  itself;  for  this  it  requires 
a  supply  of  substances  which  contain  the  constitu- 
ent elements  of  its  own  substance,  and  are  capable 
of  undergoing  transformation.  All  the  organs  to- 
gether cannot  generate  a  single  element,  carbon,  ni- 
trogen, or  a  metallic  oxide. 

When  the  quantity  of  the  food  is  too  great,  or  is 
not  capable  of  undergoing  the  necessary  transform- 
ation, or  exerts  any  peculiar  chemical  action,  the  or- 
gan itself  is  subjected  to.  a  change  :  all  poisons  act 
in  this  manner.  The  most  nutritious  substances  may 
cause  death.  In  experiments  such  as  those  describ- 
ed above,  every  condition  of  nutrition  should  be  con- 
sidered. Besides  those  matters  which  form  their 
principal  constituent  parts,  both  animals  and  plants 


60  OF  THE  ASSIMILATION  OF  CARBON. 

require  others,  the  peculiar  functions  of  which  are 
unknown.  These  are  inorganic  substances,  such  as 
common  salt,  the  total  want  of  which  is  in  animals 
inevitably  productive  of  death.  Plants,  for  the  same 
reason,  cannot  live  unless  supplied  with  certain  me- 
tallic compounds. 

If  we  knew  with  certainty  that  there  existed  a 
substance  capable,  alone,  of  nourishing  a  plant  and 
of  bringing  it  to  maturity,  we  might  be  led  to  a 
knowledge  of  the  conditions  necessary  to  the  life  of 
all  plants,  by  studying  its  characters  and  composi- 
tion. If  humus  were  such  a  substance,  it  would 
have  precisely  the  same  value  as  the  only  single  food 
which  nature  has  produced  for  animal  organization, 
namely,  milk.  (Prout.)  The  constituents  of  milk  are 
cheese  or  caseine,  a  compound  containing  nitrogen 
in  large  proportion  ;  butter,  in  which  hydrogen 
abounds ;  and  sugar  of  milk,  a  substance  with  a 
large  quantity  of  hydrogen  and  oxygen  in  the  same 
proportion  as  in  water.  It  also  contains  in  solution, 
lactate  of  soda,  phosphate  of  lime,  and  common  salt ; 
and  a  peculiar  aromatic  product  exists  in  the  butter, 
called  butyric  acid.  The  knowledge  of  the  compo- 
sition of  milk  is  a  key  to  the  conditions  necessary 
for  the  purposes  of  nutrition  of  all  animals. 

All  substances  which  are  adequate  to  the  nourish- 
ment of  animals  contain  those  materials  united, 
though  not  always  in  the  same  form;  nor  can  any 
one  be  wanting  for  a  certain  space  of  time,  without 
a  marked  effect  on  the  health  being  produced.  The 
employment  of  a  substance  as  food  presupposes  a 
knowledge  of  its  capacity  of  assimilation,  and  of  the 
conditions  under  which  this  takes  place. 

A  carnivorous  animal  dies  in  the  vacuum  of  an 
air-pump,  even  though  supplied  with  a  superabun- 
dance of  food ;  it  dies  in  the  air,  if  the  demands  of 
its  stomach  are  not  satisfied;  and  it  dies  in  pure 
oxygen  gas,  however  lavishly  nourishment  be  given 
to  it.   Is  it  hence  to  be  concluded,  that  neither  flesh, 


CONDITIONS  ESSENTIAL  TO  NUTRITION.  61 

nor  air,  nor  oxygen,  is  fitted  to  support  life  ?     Cer- 
tainly not. 

From  the  pedestal  of  the  Trajan  column  at  Rome 
we  might  chisel  out  each  single  piece  of  stone,  if 
upon  the  extraction  of  the  second  we  replaced  the 
first.  But  could  we  conclude  from  this  that  the  col- 
umn was  suspended  in  the  air,  and  not  supported  by 
a  single  piece  of  its  foundation  ?  Assuredly  not. 
Yet  the  strongest  proof  would  have  been  given  that 
each  portion  of  the  pedestal  could  be  removed,  with- 
out the  downfall  of  the  column. 

Animal  and  vegetable  physiologists,  however,  come 
to  such  conclusions  with  respect  to  the  process  of 
assimilation.  They  institute  experiments,  without 
being  acquainted  with  the  circumstances  necessary 
for  the  continuance  of  life,  —  with  the  qualities  and 
proper  nutriment  of  the  animal  or  plant  on  which 
they  operate,  —  or  with  the  nature  and  chemical  con- 
stitution of  its  organs.  These  experiments  are  con- 
sidered by  them  as  convincing  proofs,  whilst  they 
are  fitted  only  to  awaken  pity. 

Is  it  possible  to  bring  a  plant  to  maturity  by  means 
of  carbonic  acid  and  water,  without  the  aid  of  some 
substance  containing  nitrogen,  which  is  an  essential 
constituent  of  the  sap,  and  indispensable  for  its  pro- 
duction ?  Must  the  plant  not  die,  however  abundant 
the  supply  of  carbonic  a^id  may  be,  as  soon  as  the 
first  small  leaves  have  exhausted  the  nitrogen  con- 
tained in  the  seeds  ? 

Can  a  plant  be  expected  to  grow  in  Carrara  mar- 
ble, even  when  an  azotized  substance  is  supplied  to 
it,  if  the  marble  be  sprinkled  with  an  aqueous  solu- 
tion of  carbonic  acid,  which  dissolves  the  lime  and 
forms  bicarbonate  of  lime  ?  A  plant  of  the  family  of 
the  PlumbaginecB,  upon  the  leaves  of  which  fine 
hornlike,  or  scaly  processes  of  crystallized  carbonate 
of  lime  are  formed,  might  perhaps  attain  maturity 
under  such  circumstances ;  but  these  experiments 
are  only  sufficient  to  prove,  that  cresses,  gourds,  and 
balsamines,  cannot  be  nourished  by  bicarbonate  of 

6 


62  OF  THE  ASSIMILATION  OF  CARBON. 

lime,  in  the  absence  of  matter  containing  nitrogen. 
We  may,  indeed,  conclude,  that  the  salt  of  lime  acts 
as  a  poison,  since  the  development  of  plants  will  ad- 
vance further  in  pure  water,  when  lime  and  carbonic 
acid  are  not  used. 

Moist  flowers  of  sulphur  attract  oxygen  from  the 
atmosphere,  and  become  acid.  Is  it  possible  that  a 
plant  can  grow  and  flourish  in  presence  of  free  sul- 
phuric acid,  with  no  other  nourishment  than  carbonic 
acid  ?  It  is  true,  the  quantity  of  sulphuric  acid 
formed  thus  in  hours,  or  in  days,  may  be  small,  but 
the  property  of  each  particle  of  the  sulphur  to  absorb 
oxygen  and  retain  it,  is  present  every  moment. 

When  it  is  known  that  plants  require  moisture, 
carbonic  acid,  and  air,  should  we  choose,  as  the  soil 
for  experiments  on  their  growth,  sulphate  of  barytes, 
which,  from  its  nature  and  specific  gravity,  com- 
pletely prevents  the  access  of  air. 

All  these  experiments  are  valueless  for  the  deci- 
sion of  any  question.  It  is  absurd  to  take  for  them 
any  soil,  at  mere  hazard,  so  long  as  we  are  ignorant 
of  the  functions  performed  in  plants  by  those  inor- 
ganic substances  which  are  apparently  foreign  to  them. 
It  is  quite  impossible  to  mature  a  plant  of  the  fam- 
ily of  the  GraminecBj  or  of  the  JEquisetacece,  the  solid 
framework  of  which  contains  silicate  of  potash,  with- 
out silicic  acid  and  potash,  or  £r  plant  of  the  genus 
Oxalis  without  potash,  or  saline  plants  such  as  the 
saltworts  {^Salsola  and  Salicornia)  w^ithout  chloride 
of  sodium,  or  at  least  some  salt  of  similar  proper- 
ties. All  seeds  of  the  GraminecB  contain  phosphate 
of  magnesia ;  the  solid  parts  of  the  roots  of  the 
althcBa  contain  more  phosphate  of  lime  than  woody 
fibre.  Are  these  substances  merely  accidentally 
present  ?  A  plant  should  not  be  chosen  for  experi- 
ment, when  the  matter  which  it  requires  for  its 
assimilation  is  not  w^ell  known. 

What  value,  now,  can  be  attached  to  experiments 
in  which  all  those  matters  which  a  plant  requires  in 
the  process  of  assimilation,  besides   its  mere  nutri- 


ON  THE  ORIGIN  AND  ACTION  OF  HUMUS.  63 

merit,  have  been  excluded  with  the  greatest  care  1 
Can  the  laws  of  life  be  investigated  in  an  organized 
being  which  is  diseased  or  dying  ? 

The  mere  observation  of  a  wood  or  meadow  is 
infinitely  better  adapted  to  decide  so  simple  a  ques- 
tion than  all  the  trivial  experiments  under  a  glass 
globe ;  the  only  difference  is,  that  instead  of  one 
plant  there  are  thousands.  When  we  are  acquainted 
with  the  nature  of  a  single  cubic  inch  of  their  soil, 
and  know  the  composition  of  the  air  and  rain-water, 
we  are  in  possession  of  all  the  conditions  necessary 
to  their  life.  The  source  of  the  different  elements 
entering  into  the  composition  of  plants  cannot 
possibly  escape  us,  if  w^e  know  in  what  form  they 
take  up  their  nourishment,  and  compare  its  composi- 
tion with  that  of  the  vegetable  substances  which 
compose  their  structure. 

All  these  questions  will  now  be  examined  and 
discussed.  It  has  been  already  shown,  that  the 
carbon  of  plants  is  derived  from  the  atmosphere  :  it 
still  remains  for  us  to  inquire,  what  power  is  exerted 
on  vegetation  by  the  humus  of  the  soil  and  the 
inorganic  constituents  of  plants,  and  also  to  trace 
the  sources  of  their  nitrogen. 


CHAPTER   III. 

ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

It  will  be  shown  in  the  second  part  of  this  work, 
that  all  plants  and  vegetable  structures  undergo  two 
processes  of  decomposition  after  death.  One  of 
these  is  named  fermentation  ;  the  other,  putrefaction^ 
decay ^  or  eremacausis,* 

*  The  word  eremacausis  was  pi^oposed  by  the  author  some  time  since, 
in  order  to  explain  the  true  nature  of  decay;  it  is  compounded  from 
ijoiua,  by  degrees,  and  xavnig,  burning.  —  TV. 

Eremacausis  is  the  act  of  gradual  combination  of  the  combustible 


64  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

It  will  likewise  be  shown,  that  decay  is  a  slow 
process  of  combustion, —  a  process,  therefore,  in 
which  the  combustible  parts  of  a  plant  unite  with 
the  oxygen  of  the  atmosphere. 

The  decay  of  woody  fibre  (the  principal  constit- 
uent of  all  plants)  is  accompanied  by  a  phenomenon 
of  a  peculiar  kind.  This  substance,  in  contact  with 
air  or  oxygen  gas,  converts  the  latter  into  an  equal 
volume  of  carbonic  acid,  and  its  decay  ceases  upon 
the  disappearance  of  the  oxygen.  If  the  carbonic 
acid  is  removed,  and  oxygen  replaced,  its  decay 
recommences,  that  is,  it  again  converts  oxygen  into 
carbonic  acid.  Woody  fibre  consists  of  carbon  and 
the  elements  of  water ;  and  if  we  judge  only  from 
the  products  formed  during  its  decomposition,  and 
from  those  formed  by  pure  charcoal,  burned  at  a  high 
temperature,  we  might  conclude  that  the  causes 
were  the  same  in  both:  the  decay  of  woody  fibre 
proceeds,  therefore,  as  if  no  hydrogen  or  oxygen 
entered  into  its  composition.* 

A  very  long  time  is  required  for  the  completion 
of  this  process  of  combustion,  and  the  presence  of 
water  is  necessary  for  its  maintenance ;  alkalies 
promote  it,  but  acids  retard  it;  all  antiseptic  sub- 
elements  of  a  body  with  the  oxygen  of  the  air ;  a  slow  combustion  or 
oxidation. 

The  conversion  of  wood  into  humus,  the  formation  of  acetic  acid 
out  of  alcohol,  nitrification,  and  numerous  other  processes,  are  of  this 
nature.  Vegetable  juices  of  every  kind,  parts  of  animal  and  vegetable 
substances,  moist  sawdust,  blood,  &c.,  cannot  be  exposed  to  the  air, 
without  suffering  immediately  a  progressive  change  of  color  and  prop- 
erties, during  which  oxygen  is  absorbed.  These  changes  do  not  take 
place  when  water  is  excluded,  or  when  the  substances  are  exposed  to 
the  temperature  of  32°,  and  different  bodies  require  different  degrees 
of  heat,  in  order  to  effect  the  absorption  of  oxygen,  and,  consequently, 
their  eremacausis.  The  property  of  suffering  this  change  is  possessed 
in  the  highest  degree  by  substances  which  contain  nitrogen.  —  Liebig. 
Org.  Chem.     Part  2d. 

*  In  the  Appendix  to  the  Third  Report  of  the  Agriculture  of  Massa- 
chusetts, 1840,  Dr.  S.  L.  Dana  adduces  the  following  example,  to  show 
that  even  a  moist  plant  will  not  decay,  if  air  is  excluded.  A  piece  of 
a  white  birch  tree  was  taken  from  a  depth  of  twenty-five  feet  below 
the  surface,  in  Lowell.  **It  must  have  been  inhumed  there  probably 
before  the  creation  of  man,  yet  this  most  perishable  of  all  wood  is 
nearly  as  sound  as  if  cut  from  the  forest  last  fall." 


IT  EVOLVES  CARBONIC  ACID.  65. 

stances,  such  as  sulphurous  acid,  the  mercurial  salts, 
empyreumatic  oils,  &c.,  cause  its  complete  cessation. 

Woody  fibre  in  a  state  of  decay  is  the  substance 
called  humus* 

The  property  of  woody  fibre  to  convert  surround- 
ing oxygen  gas  into  carbonic  acid  diminishes  in 
proportion  as  its  decay  advances,  and  at  last  a  cer- 
tain quantity  of  a  brown  coaly-looking  substance 
remains,  in  which  this  property  is  entirely  wanting. 
This  substance  is  called  mould ;  it  is  the  product  of 
the  complete  decay  of  woody  fibre.  Mould  consti- 
tutes the  principal  part  of  all  the  strata  of  brown 
coal  and  peat. 

Humus  acts  in  the  same  manner  in  a  soil  permeable 
to  air  as  in  the  air  itself;  it  is  a  continued  source  of 
carbonic  acid,  which  it  emits  very  slowly.  An  atmo- 
sphere of  carbonic  acid,  formed  at  the  expense  of 
the  oxygen  of  the  air,  surrounds  every  particle  of 
decaying  humus.  The  cultivation  of  land,  by  tilling 
and  loosening  the  soil,  causes  a  free  and  unob- 
structed access  of  air.  An  atmosphere  of  carbonic 
acid  is  therefore  contained  in  every  fertile  soil,  and 
is  the  first  and  most  important  food  for  the  young 
plants  which  grow  in  it. 

In  spring,  when  those  organs  of  plants  are  absent 
which  nature  has  appointed  for  the  assumption  of 
nourishment  from  the  atmosphere,  the  component 
substance  of  the  seeds  is  exclusively  employed  in 
the  formation  of  the  roots.  Each  new  radicle  fibril 
which  a  plant  acquires  may  be  regarded  as  consti- 
tuting at  the  same  time  a  mouth,  a  lung,  and  a 
stomach.  The  roots  perform  the  functions  of  the 
leaves  from  the  first  moment  of  their  formation  : 
they  extract  from  the  soil  their  proper  nutriment, 
namely,  the  carbonic  acid  generated  by  the  humus. 

By  loosening  the  soil  which  surrounds  young 
plants,  we  favor  the  access  of  air,  and  the  formation 

*  The  humic  acid  of  chemists  is  a  product  of  the  decomposition  of 
humus  by  alkalies:  it  does  not  exist  in  the  humus  of  vegetable  physi- 
ologists.—  L. 

6* 


66  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

of  carbonic  acid;  and,  on  the  other  hand,  the  quan- 
tity of  their  food  is  diminished  by  every  difficulty 
which  opposes  the  renewal  of  air.  A  plant  itself 
effects  this  change  of  air  at  a  certain  period  of  its 
growth.  The  carbonic  acid,  which  protects  the 
undecayed  humus  from  further  change,  is  absorbed 
and  taken  away  by  the  fine  fibres  of  the  roots,  and 
by  the  roots  themselves ;  this  is  replaced  by  atmo- 
spheric air,  by  which  process  the  decay  is  renewed, 
and  a  fresh  portion  of  carbonic  acid  formed.  A 
plant  at  this  time  receives  its  food  both  by  the  roots 
and  by  the  organs  above  ground,  and  advances 
rapidly  to  maturity. 

When  a  plant  is  quite  matured,  and  when  the 
organs  by  which  it  obtains  food  from  the  atmosphere 
are  formed,  the  carbonic  acid  of  the  soil  is  no  fur- 
ther required. 

Deficiency  of  moisture  in  the  soil,  or  its  complete 
dryness,  does  not  now  check  the  growth  of  a  plant, 
provided  it  receives  from  the  dew  and  the  atmosphere 
as  much  as  is  requisite  for  the  process  of  assimila- 
tion. During  the  heat  of  summer  it  derives  its 
carbon  exclusively  from  the  atmosphere. 

We  do  not  know  what  height  and  strength  nature 
has  allotted  to  plants  ;  we  are  acquainted  only  with 
the  size  which  they  usually  attain.  Oaks  are  shown, 
both  in  London  and  Amsterdam,  as  remarkable  curi- 
osities, which  have  been  reared  by  Chinese  gardeners, 
and  are  only  one  foot  and  a  half  in  height,  although 
their  trunks,  barks,  leaves,  branches,  and  whole 
habitus,  evince  a  venerable  age.  The  small  parsnep 
grown  at  Teltow,*  when  placed  in  a  soil  which  yields 
as  much  nourishment  as  it  can  take  up,  increases  to 
several  pounds  in  weight. 

The  size  of  a  plant  is  proportional  to  the  surface 
of  the  organs  which  are  destined  to  convey  food  to  it. 

*  Teltow  is  a  village  near  Berlin,  where  small  parsneps  are  culti- 
vated in  a  sandy  soil;  they  are  much  esteemed,  and  weigh  rarely 
above  one  ounce.  —  L. 


GROWTH  OF  PLANTS.  57 

A  plant  gains  another  mouth  and  stomach  with  every 
new  fibre  of  root,  and  every  new  leaf. 

The  power  which  roots  possess  of  taking  up  nour- 
ishment does  not  cease  as  long  as  nutriment  is 
present.  When  the  food  of  a  plant  is  in  greater 
quantity- than  its  organs  require  for  their  own  perfect 
development,  the  superfluous  nutriment  is  not  re- 
turned to  the  soil,  but  is  employed  in  the  formation 
of  new  organs.  At  the  side  of  a  cell,  already  formed, 
another  cell  arises ;  at  the  side  of  a  twig  and  leaf, 
a  new  twig  and  a  new  leaf  are  developed.  These 
new  parts  could  not  have  been  formed  had  there  not 
been  an  excess  of  nourishment.  The  sugar  and 
mucilage  produced  in  the  seeds,  form  the  nutriment 
of  the  young  plants,  and  disappear  during  the  de- 
velopment of  the  buds,  green  sprouts,  and  leaves. 

The  power  of  absorbing  nutriment  from  the  atmo- 
sphere, with  which  the  leaves  of  plants  are  endowed, 
being  proportionate  to  the  extent  of  their  surface, 
every  increase  in  the  size  and  number  of  these  parts 
is  necessarily  attended  with  an  increase  of  nutritive 
power,  and  a  consequent  .further  development  of  new 
leaves  and  branches.  Leaves,  twigs,  and  branches, 
when  completely  matured,  as  they  do  not  become 
larger,  do  not  need  food  for  their  support.  For 
their  existence  as  organs,  they  require  only  the 
means  necessary  for  the  performance  of  the  special 
functions  to  which  they  are  destined  by  nature;  they 
do  not  exist  on  their  own  account. 

We  know  that  the  functions  of  the  leaves  and 
other  green  parts  of  plants  are  to  absorb  carbonic 
acid,  and  with  the  aid  of  light  and  moisture,  to 
appropriate  its  carbon.  These  processes  are  contin- 
ually in  operation;  they  commence  with  the  first 
formation  of  the  leaves,  and  do  not  cease  with  their 
perfect  development.  But  the  new  products  arising 
from  this  continued  assimilation  are  no  longer  em- 
ployed by  the  perfect  leaves  in  their  own  increase : 
they  serve  for  the  formation  of  woody  fibre,  and  all 
the  solid  matters  of  similar  composition.    The  leaves 


68  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

now  produce  sugar,  amylin  or  starch,  and  acids, 
which  were  previously  formed  by  the  roots,  when 
they  were  necessary  for  the  development  of  the  stem, 
buds,  leaves,  and  branches  of  the  plant. 

The  organs  of  assimilation,  at  this  period  of  their 
life,  receive  more  nourishment  from  the  atmosphere 
than  they  employ  in  their  own  sustenance;  and  when 
the  formation  of  the  woody  substance  has  advanced 
to  a  certain  extent,  the  expenditure  of  the  nutriment, 
the  supply  of  which  still  remains  the  same,  takes  a 
new  direction,  and  blossoms  are  produced.  The 
functions  of  the  leaves  of  most  plants  cease  upon 
the  ripening  of  their  fruit,  because  the  products  of 
their  action  are  no  longer  needed.  They  now  yield 
to  the  chemical  influence  of  the  oxygen  of  the  air, 
generally  suffer  a  change  in  color,  and  fall  off. 

A  peculiar  "  transformation  "  of  the  matters  con- 
tained in  all  plants  takes  place  in  the  period  between 
blossoming  and  the  ripening  of  the  fruit;  new  com- 
pounds are  produced,  which  furnish  constituents  of 
the  blossoms,  fruit,  and  seed.  An  organic  chemical 
"transformation"  is  the  separation  of  the  elements 
of  one  or  several  combinations,  and  their  reunion 
into  two  or  several  others,  which  contain  the  same 
number  of  elements,  either  grouped  in  another  man- 
ner, or  in  different  proportions.  Of  two  compounds 
formed  in  consequence  of  such  a  change,  one  remains 
as  a  component  part  of  the  blossom  or  fruit,  while 
the  other  is  separated  by  the  roots  in  the  form  of 
excrementitious  matter.  No  process  of  nutrition 
can  be  conceived  to  subsist  in  animals  or  vegetables, 
without  a  separation  of  effete  matters.  We  know, 
indeed,  that  an  organized  body  cannot  generate 
substances,  but  can  only  change  the  mode  of  their 
combination,  and  that  its  sustenance  and  reproduc- 
tion depend  upon  the  chemical  transformation  of  the 
matters  which  are  employed  as  its  nutriment,  and 
which  contain  its  own  constituent  elements. 

Whatever  we  regard  as  the  cause  of  these  trans- 
formations, whether  the  Vital  Principle,  Increase  of 


TRANSFORMATIONS  OF  ORGANIC  SUBSTANCES.  69 

Temperature,  Light,  Galvanism,  or  any  other  influ- 
ence, the  act  of  transformation  is  a  purely  chemical 
process.  Combination  and  Decomposition  can  take 
place  only  when  the  elements  are  disposed  to  these 
changes.  That  which  chemists  name  affinity  indi- 
cates only  the  degree  in  which  they  possess  this 
disposition.  It  will  be  shown,  when  considering  the 
processes  of  fermentation  and  putrefaction,  that  every 
disturbance  of  the  mutual  attraction  subsisting  be- 
tween the  elements  of  a  body  gives  rise  to  a  trans- 
formation. The  elements  arrange  themselves  accord- 
ing to  the  degrees  of  their  reciprocal  attraction  into 
new  combinations,  which  are  incapable  of  further 
change  under  the  same  conditions. 

The  products  of  these  transformations  vary  with 
their  causes,  that  is,  with  the  different  conditions  on 
which  their  production  depended ;  and  are  as  innu- 
merable as  these  conditions  themselves.  The  chem- 
ical character  of  an  acid,  for  example,  is  its  unceas- 
ing disposition  to  saturation  by  means  of  abase;* 
this  disposition  differs  in  intensity  in  different  acids ; 
but  when  it  is  satisfied,  the  acid  character  entirely 
disappears.  The  chemical  character  of  a  base  is 
exactly  the  reverse  of  this,  but  both  an  acid  and  a 
base,  notwithstanding   the  great   difference  in  their 

*  Liebig  applies  the  term  base  to  compounds  which  unite  with  acids 
and  neutralize  their  characters.  The  product  is  a  salt.  When  the 
characters  of  both  acids  and  bases  disappear  the  compound  is  neutral. 

Some  acids  contain  oxygen,  others  hydrogen.  Several  metals  form 
acids  with  oxygen ;  but  the  greater  number  of  metallic  oxides,  are,  in 
their  relations,  totally  different  from  the  acids.  They  form  conipounds, 
which,  for  the  most  part,  are  insoluble  in  water  ;  those  soluble  in  water 
have  an  alkaline  taste,  and  possess  the  property  of  restoring  the  blue 
color  of  vegetables,  which  have  been  reddened  by  acids.  These  also 
change  many  vegetable  yellows  to  red  or  brown.  The  alkalies  are 
soluble  bases.  Many  salts  redden  vegetable  blues,  and  others  again 
restore  the  blue  color  of  vegetables  reddened  by  acids ;  in  the  first 
instance,  the  salt  possesses  an  acid,  and  in  the  latter  an  alkaline, 
reaction. 

A  simple  body,  which  is  capable  of  forming  either  an  acid  or  a  base, 
is  termed  a  radical;  a  compound  radical  consists  of  two  or  three  simple 
radicals,  and  comports  itself  in  a  similar  manner  to  the  simple  radicals; 
that  is,  it  is  capable  of  forming  acids  and  bases. 


70  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

properties,  effect,  in  most   cases,  the   same  kind  of 
transformations. 

Hydrocyanic  acid  {prus sic  acid)*  and  water  con- 
tain the  elements  of  carbonic  acid,  ammonia,  urea, 
cyanuric  acid,  cyanilic  acid,  oxalic  acid,  formic  acid, 
Tnelam,  ammelin,  melamin,  azulm^in,  m^ellon,  hydro- 
mellonic  acid,  allantoin,  6fc.\  It  is  well  known,  that 
all   these   very  different  substances   can  be  obtained 

*  Cyanogen  is  considered  by  Liebig  as  a  compound  base,  and  as 
such  uniting  with  oxygen,  hydrogen,  and  most  other  nonmetaHic 
elements  and  with  the  metals.  Cyanogen  gas,  or  bicarburet  of  nitro- 
gen, is  a  compound  of  nitrogen  and  carbon,  and  was  named  from  its 
affording  a  blue  color  and  being  an  ingredient  of  Prussian  blue.  For 
the  method  of  obtaining  it,  «fec.,  see  Webster's  Chemistry,  3d  edition, 

With  hydrogen  it  constitutes  hydrocyanic  acid. 

t  Carbonic  acid  is  a  gaseous  compound  of  I  equivalent  of  carbon, 
and  2  equivalents  of  oxygen,  represented  thus,  C  -f-  20  or  c?  the  two 
dots  denoting  the  two  of  oxygen. 

Ammonia  consists  of  3  equivalents  of  hydrogen,  and  1  equivalent  of 
nitrogen,  represented  thus,  N  -f-  3H,  or  NH3. 

Urea  contains  the  elements  of  cyanate  of  ammonia  (NH4  O  -f-  C4  NO), 
and  exists  in  urine,  from  which  it  is  obtained  in  colorless,  transparent 
crystals. 

Cyanuric  acid  is  a  product  of  the  decomposition  of  chloride  of  cyan- 
ogen, of  urea,  i&c.  It  is  called  a  tribasic  acid,  and  its  hydrate  is  thus 
represented,  Cys  O3  +  3HO. 

Oxalic  acid  is  a  solid  acid  obtained  from  several  plants,  particularly- 
of  the  genera  oxalis,  rumex,  &c.  combined  with  potassa  in  roots,  and 
with  lime  in  several  kinds  of  lichens.  Oxalate  of  lime  is  found  in 
urinary  calculi.  It  is  represented  thus,  2CO -j- O  (2  equivalents  of 
carbonic  oxide  -(-  I  oxygen).  The  so-called  Essential  salt  of  lemons  is 
a  binoxalate  of  potash.     It  is  poisonous. 

Formic  acid,  obtained  from  ants,  hence  its  name.  It  is  now  obtained 
from  sugar  and  other  vegetable  substances.     Represented  by  C2  HO3. 

Melam  is  a  compound  of  C12  Nn  Hg;  it  is  a  white  powder  insoluble 
in  water,  and,  by  the  action  of  acids,  converted  into  cyanuric  acid  and 
ammonia. 

Ammelin,  a  saline  base,  represented  thus,  Cg  N5  H5  O2,  a  product  of 
the  decomposition  of  melam  by  acids  and  alkalies. 

Melamin,  a  saline  base,  product  of  the  decomposition  of  melam, 
Cs  Ne  He,  Decomposed  by  acids  into  ammonia  and  ammelid  or 
ammelin. 

Azulmen,  the  base  of  azulmic  acid,  obtained  by  the  decomposition 
of  cyanogen.     The  acid  is  Cs  H4  N4  O4. 

Mellon,  a  compound  base,  a  yellow  powder.  Decomposed  into  3 
volumes  cyanogen  and  1  volume  nitrogen  gas.     Ce  N4. 

Hydromellonic  acid  is  Ce  N4  -(-  H. 

Mlantoinc  or  allantoic  acid  occurs  in  the  allantoic  fluid  of  the  cow  ; 
it  is  formed  when  uric  acid  is  boiled  in  water  with  peroxide  of  lead. 
It  is  C4  H3  N2  O3  or  2Cy  -f-  3H0. 


TRANSFORMATIONS  OF  ORGANIC  SUBSTANCES.  71 

from  hydrocyanic  acid  and  the  elements  of  water, 
by  various  chemical  transformations. 

The  whole  process  of  nutrition  may  be  understood 
by  the  consideration  of  one  of  these  transformations. 

Hydrocyanic  acid  and  water,  for  example,  when 
brought  into  contact  with  muriatic  acid,  are  decom- 
posed into  formic  acid  and  ammonia ;  both  of  these 
products  of  decomposition  contain  the  elements  of 
hydrocyanic  acid  and  water,  although  in  another 
form,  and  arranged  in  a  different  order.  The  change 
results  from  the  strong  disposition  or  struggle  of 
muriatic  acid  to  undergo  saturation,  in  consequence 
of  which  the  hydrocyanic  acid  and  water  suffer 
mutual  decomposition.  The  nitrogen  of  the  hydro- 
cyanic acid  and  the  hydrogen  of  the  water  unite 
together  and  form  a  base,  ammonia,  with  which  the 
acid  unites ;  the  chemical  characters  of  the  acid 
being  at  the  same  time  lost,  because  its  desire  for 
saturation  is  satisfied  by  its  uniting  with  ammonia. 
Ammonia  itself  was  not  previously  present,  but  only 
its  elements,  and  the  power  to  form  it.  The  simul- 
taneous decomposition  of  hydrocyanic  acid  and  wa- 
ter in  this  instance  does  not  take  place  in  conse- 
quence of  the  chemical  affinity  of  muriatic  acid  for 
ammonia,  since  hydrocyanic  acid  and  water  contain 
no  ammonia.  An  affinity  of  one  body  for  a  second 
which  is  totally  without  the  sphere  of  its  attractions, 
or  which,  as  far  as  it  is  concerned,  does  not  exist, 
is  quite  inconceivable.  The  ammonia  in  this  case  is 
formed  only  on  account  of  the  existing  attractive 
desire  of  the  acid  for  saturation.  Hence  we  may 
perceive  how  much  these  modes  of  decomposition, 
to  which  the  name  of  transformations  or  metamorpho- 
ses has  been  especially  applied,  differ  from  the  ordi- 
nary chemical  decompositions. 

In  consequence  of  the  formation  of  ammonia,  the 
other  elements  of  hydrocyanic  acid,  namely,  carbon 
and  hydrogen,  unite  with  the  oxygen  of  the  decom- 
posed water,  and  form  formic  acid,  the  elements  of 
this  substance  with  the  power  of  combination  being 


72  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

present.  Formic  acid  here  represents  the  excre- 
mentitious  matters ;  ammonia,  the  new  substance, 
assimilated  by  an  organ  of  a  plant  or  animal. 

Each  organ  extracts  from  the  food  presented  to  it 
what  it  requires  for  its  own  sustenance ;  while  the 
remaining  elements,  which  are  not  assimilated,  com- 
bine together  and  are  separated  as  excrement.  The 
excrementitious  matters  of  one  organ  come  in  con- 
tact with  another  during  their  passage  through  the 
organism,  and  in  consequence  suffer  new  transfor- 
mations ;  the  useless  matters  rejected  by  one  organ 
containing  the  elements  for  the  nutrition  of  a  second 
and  a  third  organ:  but  at  last,  being  Capable  of  no 
further  transformations,  they  are  separated  from  the 
system  by  the  organs  destined  for  that  purpose. 
Each  part  of  an  organized  being  is  fitted  for  its 
peculiar  functions.  A  cubic  inch  of  sulphuretted 
hydrogen  introduced  into  the  lungs  would  cause 
instant  death,  but  it  is  formed,  under  a  variety  of 
circumstances,  in  the  intestinal  canal  without  any 
injurious  effect.* 

In  consequence  of  such  transformations  as  we 
have  described,  excrements  are  formed  of  various 
composition ;  some  of  these  contain  carbon  in  ex- 
cess, others  nitrogen,  and  others  again  hydrogen 
and  oxygen.  The  kidneys,  liver,  and  lungs,  are  or- 
gans of  excretion ;  the  first  separate  from  the  body 
all  those  substances  in  which  a  large  proportion  of 
nitrogen  is  contained;  the  second,  those  with  an 
excess  of  carbon;  and  the  third,  such  as  are  com- 
posed principally  of  oxygen  and  hydrogen.  Alco- 
hol, also,  and  the  volatile  oils  which  are  incapable  of 
being  assimilated,  are  exhaled  through  the  lungs, 
and  not  through  the  skin. 

Respiration  must  be  regarded  as  a  slow  process 
of  combustion  or  constant  decomposition.  If  it  be 
subject    to  the    laws  which   regulate  the    processes 

*  The  danger  of  breathing  carbonic  acid  gas  is  well  known,  but 
large  quantities  can  be  taken  into  the  stomach  with  impunity  and 
even  benefit. 


TRANSFORMATIONS  OF  ORGANIC  SUBSTANCES.  73 

of  decomposition  generally,  the  oxygen  of  the  in- 
spired air  cannot  combine  directly  with  the  carbon 
of  compounds  of  that  element  contained  in  the 
blood ;  the  hydrogen  only  can  combine  with  the 
oxygen  of  the  air,  or  undergo  a  higher  degree  of 
oxidation.  Oxygen  is  absorbed  without  uniting  with 
carbon ;  and  carbonic  acid  is  disengaged,  the  car- 
bon and  oxygen  of  which  must  be  derived  from 
matters  previously  existing  in  the  blood.* 

All  superabundant  nitrogen  is  eliminated  from  the 
body,  as  a  liquid  excrement,  through  the  urinary 
passages  ;  all  solid  substances,  incapable  of  further 
transformation,  pass  out  by  the  intestinal  canal,  and 
all  gaseous  matter  by  the  lungs. 

We  should  not  permit  ourselves  to  be  withheld 
by  the  idea  of  a  vital  principle,  from  considering  in 
a  chemical  point  of  view  the  process  of  the  transfor- 
mation of  the  food,  and  its  assimilation  by  the 
various  organs.  This  is  the  more  necessary,  as  the 
views,  hitherto  held,  have  produced  no  results,  and 
are  quite  incapable  of  useful  application. 

Is  it  truly  vitality,  w^hich  generates  sugar  in  the 
germ  for  the  nutrition  of  young  plants,  or  which 
gives  to  the  stomach  the  power  to  dissolve,  and  to 
prepare  for  assimilation,  all  the  matter  introduced 
into  it  ?  A  decoction  of  malt  possesses  as  little 
power  to  reproduce  itself,  as  the  stomach  of  a  dead 
calf;    both    are,    unquestionably,    destitute    of   life. 

*  The  examination  of  the  air  expired  by  consumptive  persons,  as 
well  as  of  their  blood,  would  doubtless  throw  much  light  on  the  nature 
of  phthisis  pulmonalis.  Considered  in  a  chemical  point  of  view,  the 
decojuposition  of  the  blood,  as  it  takes  place  in  the  lungs,  is  a  true 
process  of  putrefaction.  (See  Part  II.)  The  lungs  are  also  the  seat 
of  the  transformation  of  the  various  substances  contained  in  the  blood. 
It  certainly  well  merits  consideration,  that  the  most  approved  reme- 
dies for  counteracting  or  stopping  the  progress  of  this  frightful  malady 
are  precisely  those  which  are  found  most  efficacious  in  retarding  putre- 
faction. Thus,  it  is  well  known,  that  much  relief  is  afforded  by  a 
residence  in  works  in  which  empyreumatic  oils  are  manufactured  by- 
dry  distillation,  such  as  manufactories  for  the  preparation  of  gas  or  sal- 
ammoniac.  For  the  same  reason,  the  respiration  of  wood  vinegar 
(pyroligneous  acid),  of  chlorine,  and  certain  of  the  acids,  has  been, 
recognised  as  a  means  of  alleviating  the  disease.  —  L. 

7 


74  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

But  when  amylin  or  starch  is  introduced  into  a  de- 
coction of  malt,  it  changes,  first  into  a  gummy-like 
matter,  and  lastly  into  sugar.  Hard-boiled  albumen 
and  muscular  fibre  can  be  dissolved  in  a  decoction 
of  a  calf's  stomach,  to  which  a  few  drops  of  muria- 
tic acid  have  been  added,  precisely  as  in  the  stom- 
ach itself.^    (Schwann,  Schulz.) 

The  power,  therefore,  to  effect  transformations, 
does  not  belong  to  the  vital  principle:  each  trans- 
formation is  owing  to  a  disturbance  in  the  attraction 
of  the  elements  of  a  compound,  and  is  consequently 
a  purely  chemical  process.  There  is  no  doubt  that 
this  process  takes  place  in  another  form  from  that 
of  the  ordinary  decomposition  of  salts,  oxides,  or 
sulphurets.  But  is  it  the  fault  of  chemistry  that 
physiology  has  hitherto  taken  no  notice  of  this  new 
form  of  chemical  action  ? 

Physicians  are  accustomed  to  administer  whole 
ounces  of  borax  to  patients  suffering  under  urinary 
calculi,  when  it  is  known  that  the  bases  of  all  al- 
kaline salts  formed  by  organic  acids  are  carried 
through  the  urinary  passages  in  the  form  of  alkaline 
carbonates,  capable  of  dissolving  calculi  (Wohler). 
Is  this  rational?  The  medical  reports  state,  that 
upon  the  Rhine,  where  so  much  cream  of  tartar  is 
consumed  in  wine,  the  only  cases  of  calculous  dis- 
orders are  those  which  are  imported  from  other  dis- 
tricts. We  know  that  the  uric  acid  calculus  is 
transformed  into  the  mulberry  calculus  (which  con- 
tains oxalic  acid),  when  patients  suffering  under  the 
former  exchange  the  town  for  the  country,  where 
less  animal  and  more  vegetable  food  is  used.  Are 
all  these  circumstances  incapable  of  explanation? 

The  volatile  oil  of  the  roots  of  valerian  may  be 
obtained  from  the  oil  generated  during  the  fermen- 
tation of  potatoes  (Dumas),  and  the  oil  of  the 
SpircBa  ulmaria  from  the  crystalline  matter  of  the 

*  This  remarkable  action  has  been  completely  confirmed  in  this 
laboratory  (Giessen),  by  Dr.  Vogel,  a  highly  distinguished  young 
physiologist.  —  L. 


NATURE  OF  ORGANIC  CHEMICAL  PROCESSES.  75 

bark  of  the  willow  (Piria).  We  are  able  to  form 
in  our  laboratories  formic  acid,  oxalic  acid,  urea, 
and  the  crystalline  substances  existing  in  the  liquid 
of  the  allantois  of  the  cow,  all  products,  it  is  said, 
of  the  vital  principle.  We  see,  therefore,  that  this 
mysterious  principle  has  many  relations  in  common 
with  chemical  forces,  and  that  the  latter  can  indeed 
replace  it.  What  these  relations  are,  it  remains  for 
physiologists  to  investigate.  Truly  it  would  be  ex- 
traordinary if  this  vital  principle,  which  uses  every- 
thing for  its  own  purposes,  had  allotted  no  share 
to  chemical  forces,  which  stand  so  freely  at  its  dis- 
posal. We  shall  obtain  that  which  is  obtainable 
in  a  rational  inquiry  into  nature,  if  we  separate 
the  actions  belonging  to  chemical  powers  from  those 
which  are  subordinate  to  other  influences.  But  the 
expression  "  vital  principle  "  must  in  the  mean  time 
be  considered  as  of  equal  value  with  the  terms 
specific  or  dynamic  in  medicine  :  everything  is  specific 
which  we  cannot  explain,  and  dynamic  is  the  ex- 
planation of  all  which  we  do"  not  understand ;  the 
terms  having  been  invented  merely  for  the  purpose 
of  concealing  ignorance  by  the  application  of  learned 
epithets. 

Transformations  of  existing  compounds  are  con- 
stantly taking  place  during  the  whole  life  of  a 
plant,  in  consequence  of  which,  and  as  the  results 
of  these  transformations,  there  are  produced  gaseous 
matters  which  are  excreted  by  the  leaves  and  blos- 
soms, solid  excrements  deposited  in  the  bark,  and 
fluid  soluble  substances  which  are  eliminated  by  the 
roots.  Such  secretions  are  most  abundant  imme- 
diately before  the  formation  and  during  the  con- 
tinuance of  the  blossoms ;  they  diminish  after  the 
development  of  the  fruit.  Substances  containing  a 
large  proportion  of  carbon  are  excreted  by  the  roots 
and  absorbed  by  the  soil.  Through  the  expulsion 
of  these  matters  unfitted  for  nutrition,  the  soil  re- 
ceives again  with  usury  the  carbon  which  it  had  at 


76  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

first  yielded  to  the  young  plants  as  food,  in  the 
form  of  carbonic  acid. 

The  soluble  matter  thus  acquired  by  the  soil  is 
still  capable  of  decay  and  putrefaction,  and  by 
undergoing  these  processes  furnishes  renewed  sour- 
ces of  nutrition  to  another  generation  of  plants;  it 
becomes  humus.  The  cultivated  soil  is  thus  placed 
in  a  situation  exactly  analogous  to  that  of  forests 
and  meadows;  for  the  leaves  of  trees  which  fall  in 
the  forest  in  autumn,  and  the  old  roots  of  grass  in 
the  meadow,  are  likewise  converted  into  humus  by 
the  same  influence :  a  soil  receives  more  carbon  in 
this  form  than  its  decaying  humus  had  lost  as  car- 
bonic acid. 

Plants  do  not  exhaust  the  carbon  of  a  soil  in  the 
normal  condition  of  their  growth ;  on  the  contrary, 
they  add  to  its  quantity.  But  if  it  is  true  that  plants 
give  back  more  carbon  to  a  soil  than  they  take  from 
it,  it  is  evident  that  their  growth  must  depend  upon 
the  reception  of  nourishment  from  the  atmosphere  in 
the  form  of  carbonic  acid.  The  influence  of  humus 
upon  vegetation  is  explained  by  the  foregoing  facts 
in  the  most  clear  and  satisfactory  manner. 

Humus  does  not  nourish  plants  by  being  taken  up 
and  assimilated  in  its  unaltered  state,  but  by  pre- 
senting a  slow  and  lasting  source  of  carbonic  acid, 
which  is  absorbed  by  the  roots,  and  is  the  principal 
nutriment  of  young  plants  at  a  time  when,  being  des- 
titute of  leaves,  they  are  unable  to  extract  food  from 
the  atmosphere. 

In  former  periods  of  the  earth's  history,  its  sur- 
face was  covered  with  plants,  the  remains  of  which 
are  still  found  in  the  coal  formations.  These  plants, 
—  the  gigantic  monocotyledons,  ferns,  palms,  and 
reeds,  —  belong  to  a  class  to  which  nature  has  given 
the  power,  by  means  of  an  immense  extension  of  their 
leaves,  to  dispense  with  nourishment  from  the  soil. 
They  resemble  in  this  respect  the  plants  which  we 
raise  from  bulbs  and  tubers,  and  which  live  while 
young  upon  the  substances  contained  in  their  seed. 


ITS  USE  EXPLAINED.  77 

and  require  no  food  from  the  soil  when  their  exterior 
organs  of  nutrition  are  formed.  This  class  of  plants 
is  even  at  present  ranked  amongst  those  which  do 
not  exhaust  the  soil. 

The  necessity  of  the  existence  of  plants  such  as 
these  at  the  commencement  of  vegetation,  must  now 
be  apparent.  Humus  is  a  product  of  the  decay  of 
vegetable  matter,  and  therefore  could  not  have  ex- 
isted to  supply  the  first  plants  with  the  food  neces- 
sary for  the  development  of  the  more  delicate  kinds. 
Hence  the  plants  capable  of  flourishing  under  such 
circumstances  could  only  be  those  which  receive  their 
nourishment  from  the  air  alone.  By  their  decay, 
however,  the  soil  in  which  they  grew  became  sup- 
plied with  vegetable  matter,  and  the  progress  of 
vegetation  must  have  furnished  to  the  earth  materi- 
als adapted  for  the  development  of  those  plants, 
which  depend  upon  the  nutriment  contained  in  the 
soil,  until  those  organs  are  formed  which  are  des- 
tined for  the  assumption  of  nourishment  from  the 
atmosphere. 

The  plants  of  every  former  period  are  distinguished 
from  those  of  the  present  by  the  inconsiderable  de- 
velopment of  their  roots.  Fruit,  leaves,  seeds,  near- 
ly every  part  of  the  plants  of  a  former  world,  except 
the  roots,  are  found  in  the  brown  coal  formation. 
The  vascular  bundles,  and  the  perishable  cellular  tis- 
sue, of  which  their  roots  consisted,  have  been  the 
first  to  suffer  decomposition.  But  when  we  examine 
oaks  and  other  trees,  which  in  consequence  of  revo- 
lutions of  the  same  kind  occurring  in  later  ages  have 
undergone  the  same  changes,  we  never  find  their 
roots  absent. 

The  verdant  plants  of  warm  climates  are  very  often 
such  as  obtain  from  the  soil  only  a  point  of  attach- 
ment, and  are  not  dependent  on  it  for  their  growth. 
How  extremely  small  are  the  roots  of  the  Cactus^ 
Sedum,  and  Sempervivum,  in  proportion  to  their 
mass,  and  to  the  surface  of  their  leaves  !  Large  for- 
ests are  often  found  growing  in  soils  absolutely  des- 

7# 


78  ON  THE  ORIGIN  AND  ACTION  OF  HUMUS. 

titute  of  carbonaceous  matter;  and  the  extensive 
prairies  of  the  Western  Continent  show  that  the  car- 
bon necessary  for  the  sustenance  of  a  plant  may  be 
entirely  extracted  from  the  atmosphere.  Again,  in 
the  most  dry  and  barren  sand,  where  it  is  impossible 
for  nourishment  to  be  obtained  through  the  roots,  we 
see  the  milky-juiced  plants  attain  complete  perfec- 
tion. The  moisture  necessary  for  the  nutrition  of 
these  plants  is  derived  from  the  atmosphere,  and 
when  assimilated  is  secured  from  evaporation  by  the 
nature  of  the  juice  itself.  Caoutchouc  and  wax:, 
which  are  formed  in  these  plants,  surround  the  water, 
as  in  oily  emulsions,  with  an  impenetrable  envelope 
by  which  the  fluid  is  retained,  in  the  same  manner  as 
milk  is  prevented  from  evaporating  by  the  skin 
which  forms  upon  it.  These  plants,  therefore,  be- 
come turgid  with  their  juices. 

Particular  examples  might  be  cited  of  plants,  which 
have  been  brought  to  mgiturity,  upon  a  small  scale, 
without  the  assistance  of  mould ;  but  fresh  proofs 
of  the  accuracy  of  our  theory  respecting  the  origin 
of  carbon  would  be  superfluous  and  useless,  and 
could  not  render  more  striking,  or  more  convincing, 
the  arguments  already  adduced.  It  must  not,  how- 
ever, be  left  unmentioned,  that  common  wood  char- 
coal, by  virtue  merely  of  its  ordinary  well-known 
properties,  can  completely  replace  vegetable  mould 
or  humus.  The  experiments  of  Lukas,  which  are 
appended  to  this  work,  spare  me  all  further  remarks 
upon  its  eflicacy. 

Plants  thrive  in  powdered  charcoal,  and  may  be 
brought  to  blossom  and  bear  fruit  if  exposed  to  the 
influence  of  the  rain  and  the  atmosphere ;  the  char- 
coal may  be  previously  heated  to  redness.  Charcoal 
is  the  most  "  indifferent "  and  most  unchangeable 
substance  known ;  it  may  be  kept  for  centuries  with- 
out change,  and  is  therefore  not  subject  to  decompo-^^ 
sition.  The  only  substances  which  it  can  yield  to 
plants  are  some  salts,  which  it  contains,  amongst 
which  is  silicate  of  potash.     It  is  known,  however, 


I 


NOT  INDISPENSABLE  FOR  PLANTS.  79 


to  possess  the  power  of  condensing  gases  within  its 
pores,  and  particularly  carbonic  acid.  And  it  is  by 
virtue  of  this  power  that  the  roots  of  plants  are  sup- 
plied in  charcoal,  exactly  as  in  humus,  with  an  at- 
mosphere of  carbonic  acid  and  air,  which  is  renewed 
as  quickly  as  it  is  abstracted. 

In  charcoal  powder,  which  had  been  used  for  this 
purpose  by  Lukas  for  several  years,  Buchner  found  a 
brown  substance  soluble  in  alkalies.  This  substance 
was  evidently  due  to  the  secretions  from  the  roots 
of  the  plants  which  grew  in  it. 

A  plant  placed  in  a  closed  vessel  in  which  the  air, 
and  therefore  the  carbonic  acid,  cannot  be  renewed, 
dies  exactly  as  it  would  do  in  the  vacuum  of  an  air- 
pump,  or  in  an  atmosphere  of  nitrogen  or  carbonic 
acid,  even  thoUgh  its  roots  be  fixed  in  the  richest 
mould.* 

Plants  do  not,  however,  attain  maturity,  under  or- 
dinary circumstances,  in  charcoal  powder,  when  they 
are  moistened  with  pure  distilled  water  instead  of 
rain  or  river  water.  Rain  water  must,  therefore,  con- 
tain within  it  one  of  the  essentials  of  vegetable  life ; 
and  it  will  be  shown,  that  this  is  the  presence  of  a 
compound  containing  nitrogen,  the  exclusion  of  which 
entirely  deprives  humus  and  charcoal  of  their  influ- 
ence upon  vegetation. 

*  A  few  years  since  I  had  an  opportunity  of  observing  a  striking  in- 
stance of  the  effect  of  carbonic  acid  upon  vegetation  in  the  volcanic 
island  of  St.  Michael  (Azores).  The  gas  issued  from  a  fissure  in  the 
base  of  a  hill  of  trachyte  and  tufFa  from  which  a  level  field  of  some 
acres  extended.  This  field,  at  the  time  of  my  visit,  was  in  part  covered 
with  Indian  corn.  The  corn  at  the  distance  of  ten  or  fifteen  yards  from 
the  fissure,  was  nearly  full  grown,  and  of  the  usual  height,  but  the 
height  regularly  diminished  until  within  five  or  six  feet  of  the  hill, 
where  it  attained  but  a  few  inches.  This  eflfect  was  owing  to  the  great 
specific  gravity  of  the  carbonic  acid,  and  its  spreading  upon  the  ground, 
but  as  the  distance  increased,  and  it  became  more  and  more  mingled 
witli  atmospheric  air,  it  had  produced  less  and  less  effect.  —  IV. 


80  ON  THE  ASSIMILATION  OF  HYDROGEN 


CHAPTER  IV. 

ON  THE  ASSIMILATION  OF  HYDROGEN. 

The  atmosphere  contains  the  principal  food  of 
plants  in  the  form  of  carbonic  acid,  in  the  state, 
therefore,  of  an  oxide.  The  solid  part  of  plants 
(woody  fibre)  contains  carbon  and  the  constituents 
of  water,  or  the  elements  of  carbonic  acid,  together- 
with  a  certain  quantity  of  hydrogen.  It  has  former- 
ly been  mentioned  that  water  consists  of  the  two 
gases,  oxygen  and  hydrogen.  The  range  of  affinity 
possessed  by  both  these  elements  is  so  extensive,  that 
numerous  causes  occur  which  effect  the  decomposi- 
tion of  water.  Indeed,  there  is  no  compound  which 
plays  a  more  general  or  more  important  part  in  the 
phenomena  of  combination  and  decomposition.  We 
can  conceive  the  wood  to  arise  from  a  combination 
of  the  carbon  of  the  carbonic  acid  with  the  elements 
of  water,  under  the  influence  of  solar  light.  In  this 
case,  72*35  parts  of  oxygen,  by  weight,  must  be  sep- 
arated as  a  gas  for  every  27*65  parts  of  carbon, 
which  are  assimilated  by  a  plant ;  for  this  is  the 
composition  of  carbonic  acid  in  100  parts.  Or,  what 
is  much  more  probable,  plants,  under  the  same  cir- 
cumstances, may  decompose  water,  the  hydrogen  of 
which  is  assimilated  along  with  carbonic  acid,  whilst 
its  oxygen  is  separated.  If  the  latter  change  takes 
place,  8-04  parts  of  hydrogen  must  unite  with  100 
parts  of  carbonic  acid,  in  order  to  form  woody  fibre, 
and  the  72*35  parts  by  weight  of  oxygen,  which  was 
in  combination  with  the  hydrogen  of  the  water,  and 
which  exactly  corresponds  in  quantity  with  the  oxy- 
gen contained  in  the  carbonic  acid,  must  be  separ- 
ated in  a  gaseous  form. 

Each  acre  of  land,  which  produces  10  cwts.  of 
carbon,  gives  annually  to  the  atmosphere  2865  lbs.  of 
free  oxygen  gas.     The  specific  weight  of  oxygen  is 


BY  THE  DECOMPOSITION  OF  WATER,  81 

expressed  by  the  number  1-1026;  hence  1  cubic  me- 
tre of  oxygen  weighs  3-167  lbs.,  and  2865  lbs.  of 
oxygen  correspond  to  908  cubic  metres,  or  32,007 
cubic  feet. 

An  acre  of  meadow,  wood,  or  cultivated  land  in 
general  replaces,  therefore,  in  the  atmosphere  as 
much  oxygen  as  is  exhausted  by  10  cwts.  of  carbon, 
either  in  its  ordinary  combustion  in  the  air  or  in  the 
respiratory  process  of  animals. 

It  has  been  mentioned  at  a  former  page  that  pure 
woody  fibre  contains  carbon  and  the  component  parts 
of  water,  but  that  ordinary  wood  contains  more  hy- 
drogen than  corresponds  to  this  proportion.  This 
excess  is  owing  to  the  presence  of  the  green  princi- 
ple of  the  leaf,  wax,  resin,  and  other  bodies  rich  in 
hydrogen.  Water  must  be  decomposed,  in  order  to 
furnish  the  excess  of  this  element,  and  consequently 
one  equivalent  of  oxygen  must  be  given  back  to  the 
atmosphere  for  every  equivalent  of  hydrogen  appro- 
priated by  a  plant  to  the  production  of  those  sub- 
stances. The  quantity  of  oxygen  thus  set  at  liberty 
cannot  be  insignificant,  for  the  atmosphere  must  re- 
ceive 547  cubic  feet  of  oxygen  for  every  pound  of 
hydrogen  assimilated. 

It  has  already  been  stated,  that  a  plant,  in  the 
formation  of  woody  fibre,  must  always  yield  to  the 
atmosphere  the  same  proportional  quantity  of  oxy- 
gen ;  that  the  volume  of  this  gas  set  free  would  be 
the  same  whether  it  were  due  to  the  decomposition 
of  carbonic  acid  or  of  water.  A  little  consideration 
will  show  that  this  must  be  the  case.  It  has  repeat- 
edly been  stated,  that  woody  fibre  contains  carbon 
in  combination  with  oxygen  and  hydrogen  in  the 
same  proportion  in  which  they  exist  in  water.  Water 
contains  1  equivalent  of  each  element,  whilst  carbon- 
ic acid  consists  of  1  equivalent  of  carbon,  united  to 
2  equivalents  of  oxygen.  In  the  formation  of  woody 
fibre,  2  equivalents  of  oxygen  must  therefore  be  lib- 
erated. The  woody  fibre  can  only  be  formed  in  one 
of  two  ways :    either  the   carbon   of  carbonic   acid 


82  ASSIMILATION  OF  HYDROGEN 

unites  directly  with  water,  or  the  hydrogen  of  water 
combines  with  the  oxygen  of  the  carbonic  acid.  In 
the  former  of  these  cases,  the  two  equivalents  of  ox- 
ygen in  the  carbonic  acid  must  be  liberated;  in  the 
latter,  two  atoms  of  water  must  be  decomposed,  the 
hydrogen  of  which  unites  with  the  oxygen  of  the 
carbonic  acid,  whilst  the  oxygen  of  the  water,  thus 
set  free,  is  disengaged  in  the  state  of  a  gas.  It 
was  considered  most  probable  that  the  latter  was 
the  case. 

From  their  generating  caoutchouc,  wax,  fats,  and 
volatile  oils  containing  hydrogen  in  large  quantity, 
and  no  oxygen,  we  may  be  certain  that  plants  pos- 
sess the  property  of  decomposing  water,  because 
from  no  other  body  could  they  obtain  the  hydrogen 
of  those  matters.  It  has  also  been  proved  by  the 
observations  of  Humboldt  on  the  fungi,  that  water 
may  be  decomposed  without  the  assimilation  of  hy- 
drogen. Water  is  -a  remarkable  combination  of 
two  elements,  which  have  the  power  to  separate 
themselves  from  one  another,  in  innumerable  pro- 
cesses, in  a  manner  imperceptible  to  our  senses  ;  while 
carbonic  acid,  on  the  contrary,  is  only  decomposable 
by  violent  chemical  action. 

Most  vegetable  structures  contain  hydrogen  in 
the  form  of  water,  which  can  be  separated  as  such, 
and  replaced  by  other  bodies ;  but  the  hydrogen 
which  is  essential  to  their  constitution  cannot  pos- 
sibly exist  in  the  state  of  water. 

All  the  hydrogen  necessary  for  the  formation  of 
an  organic  compound  is  supplied  to  a  plant  by  the 
decomposition  of  water.  The  process  of  assimila- 
tion, in  its  most  simple  form,  consists  in  the  extrac- 
tion of  hydrogen  from  water,  and  carbon  from  car- 
bonic acid,  in  consequence  of  which,  either  all  the 
oxygen  of  the  water  and  carbonic  acid  is  separated, 
as  in  the  formation  of  caoutchouc,  the  volatile  oils 
which  contain  no  oxygen,  and  other  similar  sub- 
stances, or  only  a  part  of  it  is  exhaled. 

The  known  composition  of  the  organic  compounds 


BY  THE  DECOMPOSITION  OF  WATER.  83 

most  generally  present  in  vegetables,  enables  us  to 
state  in  definite  proportions  the  quantity  of  oxygen 
separated  during  their  formation. 

36  eq.  carbonic  acid  and  22  eq.  hydrogen  derived  )       „r    j     ni 
from  22  eq.  water  .      ^.         .         ^  =^  fVoody  Fibre, 

with  the  separation  of  72  eq.  oxygen. 

36  eq.  carbonic  acid  and  36  eq.  hydrogen  derived  > ^ 

from  36  eq.  water  .         .         .         .  3         ^^^''» 

with  the  separation  of  72  eq.  oxygen. 

36  eq.  carbonic  acid  and  30  eq.  hydrogen  derived  ) o.      t 

from  30  eq.  water  .         .         .         .  5  —  ^^^^^^> 

with  the  separation  of  72  eq.  oxygen. 

36  eq.  carbonic  acid  and  16  eq.  hydrogen  derived  ) rp       •    a   a 

from  1 6  eq.  water  .         .         .         .  5 "  ^  ^^'^^^  -^"^^ 

with  the  separation  of  64  eq.  oxygen. 

36  eq.  carbonic  acid  and  18  eq.  hydrogen  derived  > rp    .     •    /i  •  j 

from  18  eq.  water  ....         ^  — lartanc  Jiaa, 

with  the  separation  of  45  eq.  oxygen. 

36  eq.  carbonic  acid  and  18  eq.  hydrogen  derived  > jif^7,v  add 

from  18  eq.  water  ....  3  ' 

with  the  separation  of  54  eq.  oxygen. 
36  eq.  carbonic  acid  and  24  eq.  hydrogen  derived  T  ^  ^  .^    .  Turpentine, 
trom  24  eq.  water  .        .         .        .  i  j        r  t 

with  the  separation  of  84  eq.  oxygen. 

It  will  readily  be  perceived,  that  the  formation 
of  the  acids  is  accompanied  with  the  smallest 
separation  of  oxygen ;  that  the  amount  of  oxygen 
set  free  increases  with  the  production  of  the  so- 
named  neutral  substances,  and  reaches  its  maximum 
in  the  formation  of  the  oils.  Fruits  remain  acid  in 
cold  summers ;  while  the  most  numerous  trees  under 
the  tropics  are  those  which  produce  oils,  caoutchouc, 
and  other  substances  containing  very  little  oxygen. 
The  action  of  sunshine  and  influence  of  heat  upon 
the  ripening  of  fruit  is  thus,  in  a  certain  measure, 
represented  by  the  numbers  above  cited. 

The  green  resinous  principle  of  the  leaf  diminishes 
in  quantity,  while  oxygen  is  absorbed,  when  fruits' 
are  ripened  in  the  dark;  red  and  yellow  coloring 
matters  are  formed;  tartaric,  citric,  and  tannic  acids 
disappear,  and  are  replaced  by  sugar,  amylin,  or 
gum.  6  eq.  Tartaric  Acid,  by  absorbing  6  eq.  oxy- 
gen from  the  air,  form  Grape  Sugar,  with  the  separa- 
tion of  12  eq.  carbonic  acid.  1  eq.  Tannic  Acid, 
by  absorbing  8  eq.  oxygen  from  the  air,  and  4  eq. 


84  ASSIMILATION  OF  HYDROGEN. 

water,  form  1  eq.  of  Amylin,  or  starch,  with  separa- 
tion of  6  eq.  carbonic  acid. 

We  can  explain,  in  a  similar  manner,  the  forma- 
tion of  all  the  component  substances  of  plants 
which  contain  no  nitrogen,  whether  they  are  pro- 
duced from  carbonic  acid  and  water,  with  separation 
of  oxygen,  or  by  the  conversion  of  one  substance 
into  the  other,  by  the  assimilation  of  oxygen  and 
separation  of  carbonic  acid.  We  do  not  know  in 
what  form  the  production  of  these  constituents  takes 
place;  in  this  respect,  the  representation  of  their 
formation  which  we  have  given  must  not  be  received 
in  an  absolute  sense,  it  being  intended  only  to  ren- 
der the  nature  of  the  process  more  capable  of  ap- 
prehension; but  it  must  not  be  forgotten,  that  if  the 
conversion  of  tartaric  acid  into  sugar,  in  grapes,  be 
considered  as  a  fact,  it  must  take  place  under  all 
circumstances  in  the  same  proportions. 

The  vital  process  in  plants  is,  with  reference  to 
the  point  we  have  been  considering,  the  very  re- 
verse of  the  chemical  processes  engaged  in  the  for- 
mation of  salts.  Carbonic  acid,  zinc,  and  water, 
when  brought  into  contact,  act  upon  one  another, 
and  hydrogen  is  separated^  while  a  white  pulverulent 
compound  is  formed,  which  contains  carbonic  acid, 
zinc,  and  the  oxygen  of  the  water.  A  living  plant 
represents  the  zinc  in  this  process :  but  the  process 
of  assimilation  gives  rise  to  compounds,  which  con- 
tain the  elements  of  carbonic  acid  and  the  hydrogen 
of  water,  whilst  oxygen  is  separated. 

Decay  has  been  described  above  as  the  great 
operation  of  nature,  by  which  that  oxygen,  which 
was  assimilated  by  plants  during  life,  is  again  re- 
turned to  the  atmosphere.  During  the  progress  of 
growth,  plants  appropriate  carbon  in  the  form  of 
carbonic  acid,  and  hydrogen  from  the  decomposition 
of  water,  the  oxygen  of  which  is  set  free,  together 
with  a  part  of  all  of  that  contained  in  the  carbonic 
acid.  In  the  process  of  putrefaction,  a  quantity  of 
water,  exactly  corresponding  to  that  of  the  hydro- 


pT'  SOURCE  AND  ASSIMILATION  OF  NITROGEN.        85 

gen,  is  again  formed  by  extraction  of  oxygen  from 
the  air ;  while  all  the  oxygen  of  the  organic  matter 
is  returned  to  the  atmosphere  in  the  form  of  carbonic 
acid.  Vegetable  matters  can  emit  carbonic  acid, 
during  their  decay,  only  in  proportion  to  the  quan- 
tity of  oxygen  which  they  contain ;  acids,  therefore, 
yield  more  carbonic  acid  than  neutral  compounds ; 
while  fatty  acids,  resin,  and  wax,  do  not  putrefy; 
they  remain  in  the  soil  without  any  apparent  change. 
The  numerous  springs  which  emit  carbonic  acid 
in  the  neighborhood  of  extinct  volcanoes,  must  be 
regarded  as  another  means  of  compensating  for  the 
carbonic  acid  absorbed  and  retained  by  plants  dur- 
ing life,  and  consequently  as  a  source  by  which 
oxygen  is  supplied  to  the  atmosphere.  Bischof 
calculated  that  the  springs  of  carbonic  acid  in  the 
Eifel  (a  volcanic  district  near  Coblenz)  send  into 
the  air  every  day  more  than  99,000  lbs.  of  carbonic 
acid,  corresponding  to  71,000  lbs.  of  pure  oxygen. 


CHAPTER  V. 

ON  THE  ORIGIN  AND  ASSIMILATION  OF  NITROGEN. 

We  cannot  suppose  that  a  plant  could  attain 
maturity,  even  in  the  richest  vegetable  mould,  with- 
out the  presence  of  matter  containing  nitrogen ; 
since  we  know  that  nitrogen  exists  in  every  part  of 
the  vegetable  structure.  The  first  and  most  impor- 
tant question  to  be  solved,  therefore,  is :  How  and 
in  what  form  does  nature  furnish  nitrogen  to  vege- 
table albumen,  and  gluten,  to  fruits  and  seeds  1 

This  question  is  susceptible  of  a  very  simple  solu- 
tion. 

Plants,  as  we  know,  grow  perfectly  well  in  pure 
charcoal,  if  supplied  at  the  same  time  with  rain- 
water. Rain-water  can  contain  nitrogen  only  in 
two  forms,  either  as  dissolved  atmospheric  air,  or  as 

8 


86  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

ammonia^  which  consists  of  this  element  and  hydro- 
gen. Now,  the  nitrogen  of  the  air  cannot  be  made 
to  enter  into  combination  with  any  element  except 
oxygen,  even  by  the  employment  of  the  most  power- 
ful chemical  means.  We  have  not  the  slightest 
reason  for  believing  that  the  nitrogen  of  the  atmo- 
sphere takes  part  in  the  processes  of  assimilation  of 
plants  and  animals ;  on  the  contrary,  we  know  that 
many  plants  emit  the  nitrogen  which  is  absorbed  by 
their  roots,  either  in  the  gaseous  form,  or  in  solution 
in  water.  But  there  are  on  the  other  hand  numerous 
facts,  showing,  that  the  formation  in  plants  of  sub- 
stances containing  nitrogen,  such  as  gluten,  takes 
place  in  proportion  to  the  quantity  of  this  element 
which  is  conveyed  to  their  roots  in  the  state  of 
ammonia,*  derived  from  the  putrefaction  of  animal 
matter. 

Ammonia,  too,  is  capable  of  undergoing  such  a 
multitude  of  transformations,  when  in  contact  with 
other  bodies,  that  in  this  respect  it  is  not  inferior  to 
water,  which  possesses  the  same  property  in  an 
eminent  degree.  It  possesses  properties  which  we 
do  not  find  in  any  other  compound  of  nitrogen : 
when  pure,  it  is  extremely  soluble  in  water;  it  forms 
soluble  compounds  with  all  the  acids ;  and  when  in 
contact  with  certain  other  substances,  it  completely 
resigns  its  character  as  an  alkali,  and  is  capable  of 
assuming  the  most  various  and  opposite  forms. 
Formate  of  ammonia  f  changes,  under  the  influence 
of  a  high  temperature,  into  hydrocyanic  acid  and 
water,  without  the  separation  of  any  of  its  elements. 

*  Ammonia  is  a  compound  gas,  consisting  of  one  volume  of  nitrogen 
and  three  volumes  of  hydrogen.  It  is  produced  during  the  decompo- 
sition of  many  animal  substances.  It  is  given  off  when  sal-ammoniac 
and  lime  are  rubbed  together.     It  was  formerly  called  volatile  alkali. 

t  Formic  acid  (p.  70.  n.)  is  also  obtained  from  sugar  and  many  other 
vegetable  substances ;  a  pound  of  sugar  yields  a  quantity  capable  of 
saturating  five  or  six  ounces  of  carbonate  of  lime.  A  process  for 
obtaining  it  has  been  given  by  Emmet  in  the  American  Journal^  Vol. 
XXXII.  p.  140.  See  details  in  Webster's  Manual  of  Chemistry,  3d 
edition,  p.  374. 

Its  composition  is  carbon  2,  water  3.  With  ammonia  and  other 
bases  it  yields  the  salts  called  formates. 


SOURCE  AND  ASSIMILATION  OF  NITROGEN.  87 

Ammonia  forms  urea,*  with  cyanic  acid,t  and  a 
series  of  crystalline  compounds,  with  the  volatile 
oils  of  mustard  and  bitter  almonds.  It  changes 
into  splendid  blue  or  red  coloring  matters,  when  in 
contact  with  the  bitter  constituent  of  the  bark  of 
the  apple-tree  (^phloridzin),  with  the  sweet  principle 
of  the  Variolaria  dealhata  (^orcin)^  or  with  the  taste- 
less matter  of  the  Rocella  tinctoria  (^erythrin).  All 
blue  coloring  matters  which  are  reddened  by  acids, 
and  all  red  coloring  substances  which  are  rendered 
blue  by  alkalies,  contain  nitrogen,  but  not  in  the 
form  of  a  base. 

These  facts  are  not  sufficient  to  establish  the 
opinion  that  it  is  ammonia  which  affords  all  vegeta- 
bles, without  exception,  the  nitrogen  which  enters 
into  the  composition  of  their  constituent  substances. 
Considerations  of  another  kind,  however,  give  to 
this  opinion  a  degree  of  certainty  which  completely 
excludes  all  other  views  of  the  matter. 

Let  us  picture  to  ourselves  the  condition  of  a 
well-cultured  farm,  so  large  as  to  be  independent  of 
assistance  from  other  quarters.  On  this  extent  of 
land  there  is  a  certain  quantity  of  nitrogen  contained 
both  in  corn  and  fruit  which  it  produces,  and  in  the 
men  and  animals  which  feed  upon  them,  and  also  in 
their  excrements.  We  shall  suppose  this  quantity 
to  be  known.  The  land  is  cultivated  without  the 
importation  of  any  foreign  substance  containing 
nitrogen.  Now,  the  products  of  this  farm  must  be 
exchanged  every  year  for  money,  and  other  necessa- 
ries of  life  —  for  bodies,  therefore,  which  contain  no 
nitrogen.  A  certain  proportion  of  nitrogen  is  ex- 
ported with  corn  and  cattle ;  and  this  exportation 
takes  place  every  year,  without  the  smallest  com- 
pensation ;  yet  after  a  given  number  of  years,  the 
quantity  of  nitrogen  will  be  found  to  have  increased. 

*  Urea  was  discovered  in  urine,  being  a  constituent  of  uric  acid.  It 
contains  the  elements  of  cyanate  of  ammonia  (NH4  O  -f-  C4  NO). 

t  This  acid  consists  of  1  cyanogen  and  1  oxygen.  See  Webster's 
Chemistry^  p.  398. 


88  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

Whence,  we  may  ask,  comes  this  increase  of  nitro- 
gen ?  The  nitrogen  in  the  excrements  cannot  repro- 
duce itself,  and  the  earth  cannot  yield  it.  Plants, 
and  consequently  animals,  must,  therefore,  derive 
their  nitrogen  from  the  atmosphere. 

It  will  in  a  subsequent  part  of  this  work  be  shown, 
that  the  last  products  of  the  decay  and  putrefaction 
of  animal  bodies  present  themselves  in  two  different 
forms.  They  are  in  the  form  of  a  combination  of 
hydrogen  and  nitrogen,  —  ammonia^  —  in  the  tem- 
perate and  cold  climates,  and  in  that  of  a  compound 
containing  oxygen,  —  nitric  acid,  —  in  the  tropics 
and  hot  climates.  The  formation  of  the  latter  is  pre- 
ceded by  the  production  of  the  first.  Ammonia  is 
the  last  product  of  the  putrefaction  of  animal  bodies  ; 
nitric  acid  is  the  product  of  the  transformation  of 
ammonia.  A  generation  of  a  thousand  million  men 
is  renewed  every  thirty  years  :  thousands  of  millions 
of  animals  cease  to  live,  and  are  reproduced,  in  a 
much  shorter  period.  Where  is  the  nitrogen  which 
they  contained  during  life  ?  There  is  no  question 
which  can  be  answered  with  more  positive  certainty. 
All  animal  bodies  during  their  decay  yield  the  nitro- 
gen which  they  contain  to  the  atmosphere,  in  the 
form  of  ammonia.  Even  in  the  bodies  buried  sixty 
feet  under  ground  in  the  churchyard  of  the  Eglise 
des  Innocens,  at  Paris,  all  the  nitrogen  contained  in 
the  adipocire  was  in  the  state  of  ammonia."^  Ammo- 
nia is  the  simplest  of  all  compounds  of  nitrogen; 
and  hydrogen  is  the  element  for  which  nitrogen  pos- 
sesses the  most  powerful  affinity. 

The  nitrogen  of  putrefied  animals  is  contained  in 
the  atmosphere   as   ammonia,  in  the   form  of  a   gas 

*  In  1786  -  7,  when  this  churchyard  was  cleared  out,  it  was  discov- 
ered that  many  of  the  bodies  had  been  converted  into  a  soapy  white 
substance.  Fourcroy  attempted  to  prove  that  the  fatty  body  was  an 
ammoniacal  soap,  containing  phosphate  of  Jime,  that  the  fat  was  simi- 
lar to  spermaceti  and  to  wax,  hence  he  called  it  adipocire.  Its  melting 
point  was  126.5°  F. 

For  notice  of  the  analysis  and  opinions  of  other  chemists,  see  Ure's 
Dictionary  of  Arts  and  ManufactureSy  p.  14. 


PRODUCTS  OF  PUTREFACTION.  89 

which  is  capable  of  entering  into  combination  with 
carbonic  acid  and  of  forming  a  volatile  salt.  Am- 
monia in  its  gaseous  form,  as  well  as  all  its  volatile 
compounds,  is  of  extreme  solubility  in  water.*  Am- 
monia, therefore,  cannot  remain  long  in  the  atmo- 
sphere, as  every  shower  of  rain  must  condense  it,  and 
convey  it  to  the  surface  of  the  earth.  Hence  also, 
rain-water  must  at  all  times  contain  ammonia,  though 
not  always  in  equal  quantity.  It  must  be  greater  in 
summer  than  in  spring  or  in  winter,  because  the  in- 
tervals of  time  between  the  showers  are  in  summer 
greater ;  and  when  several  wet  days  occur,  the  rain 
of  the  first  must  contain  more  of  it  than  that  of  the 
second.  The  rain  of  a  thunder-storm,  after  a  long- 
protracted  drought,  ought  for  this  reason  to  contain 
the  greatest  quantity  which  is  conveyed  to  the  earth 
at  one  time. 

But  we  have  formerly  stated,  that  all  the  analyses 
of  atmospheric  air  hitherto  made  have  failed  to  de- 
monstrate the  presence  of  ammonia,  although,  ac- 
cording to  our  view,  it  can  never  be  absent.  Is  it 
possible  that  it  could  have  escaped  our  most  delicate 
and  most  exact  apparatus  ?  The  quantity  of  nitro- 
gen contained  in  a  cubic  foot  of  air  is  certainly  ex- 
tremely small,  but,  notwithstanding  this,  the  sum  of 
the  quantities  of  nitrogen  from  thousands  and  mil- 
lions of  dead  animals  is  more  than  sufficient  to  sup- 
ply all  those  living  at  one  time  with  this  element. 

From  the  tension  of  aqueous  vapor  at  15°  C.  (59° 
F.)  =  6,98  lines  (Paris  measure),  and  from  its  known 
specific  gravity  at  0°  C.  (32°  F.),  it  follows  that 
when  the  temperature  of  the  air  is  59°  F.  and  the 
height  of  the  barometer  28'',  1  cubic  metre  or  35-3 
cubic  feet  of  aqueous  vapor  are  contained  in  487 
cubic  metres,  or  17,198  cubic  feet  of  air;  35-3  cubic 
feet  of  aqueous  vapor  weigh  about  1.65  lb.  Conse- 
quently, if  we  suppose  that  the  air  saturated  with 
moisture  at  59°  F.  allows  all  the  water  which  it  con- 

*  According  to  Dr.  Thomson,  water  absorbs  780  times  its  bulk  of 
ammonia. 

8* 


90  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

tains  in  the  gaseous  form  to  fall  as  rain,  then  1*1 
pound  of  rain  water  must  be  obtained  from  every 
II5477  cubic  feet  of  air.  The  whole  quantity  of  am- 
monia contained  in  the  same  number  of  cubic  feet 
will  also  be  returned  to  the  earth  in  this  one  pound 
of  rain-water.  But  if  the  11,477  cubic  feet  of  air 
contain  a  single  grain  of  ammonia,  then  ten  cubic 
inches,  —  the  quantity  usually  employed  in  an  analy- 
sis,—  must  contain  only  0.000,000050  of  a  grain. 
This  extremely  small  proportion  is  absolutely  inap- 
preciable by  the  most  delicate  and  best  eudiometer ;  * 
it  might  be  classed  among  the  errors  of  observation, 
even  were  its  quantity  ten  thousand  times  greater. 
But  the  detection  of  ammonia  must  be  much  more 
easy  when  a  pound  of  rain-water  is  examined,  for 
this  contains  all  the  gas  that  was  diffused  through 
11,477  cubic  feet  of  air. 

If  a  pound  of  rain-water  contain  only  Jth  of  a  grain 
of  ammonia,  then  a  field  of  26,910  square  feet  must 
receive  annually  upwards  of  88  lbs.  of  ammonia,  or 
71  lbs.  of  nitrogen  ;  for  by  the  observations  of  Schu- 
bler,  which  were  formerly  alluded  to,  about  770,000 
lbs.  of  rain  fall  over  this  surface  in  four  months,  and 
consequently  the  annual  fall  must  be  2,310,000  lbs. 
This  is  much  more  nitrogen  than  is  contained  in  the 
form  of  vegetable  albumen  and  gluten,  in  2920  lbs. 
of  wood,  3085  lbs.  of  hay,  or  200  cwt.  of  beet-root, 
which  are  the  yearly  produce  of  such  a  field ;  but  it 
is  less  than  the  straw,  roots,  and  grain  of  corn,  which 
might  grow  on  the  same  surface,  would  contain.f 

*  A  eudiometer  is  an  instrument  used  in  the  analyses  of  the  atmo- 
sphere. It  means  a  measure  of  purity.  It  is  also  used  in  the  analysis 
of  mixtures  of  gases.  Several  varieties  are  described  in  Webster's 
Manual^  p.  137. 

t  The  advocates  of  the  importance  of  humus  as  a  nourishment  for 
plants,  being  driven  from  their  position  by  the  facts  brought  forward  in 
the  preceding  chapters,  have  found  in  the  ammonia  of  the  atmosphere 
an  explanation  of  the  manner  in  which  humus  acquires  its  solubility, 
and  therefore  its  capability  of  being  assimilated  by  plants.  Now,  it  is 
very  true  that  humic  acid  is  soluble  in  ammonia ;  but  the  humic  acid 
of  chemists  is  not  contained  in  soils.  Were  it  so,  on  treating  mould  with 
water  we  should  obtain  a  dark-colored  solution  of  humate  of  ammonia. 
But  we  obtain  a  solution  which  is  entirely  devoid  of  this  acid.     It  cau- 


EXISTENCE  OF  AMMONIA  IN  RAIN.  91 

Experiments  made  in  this  laboratory  (Giessen) 
with  the  greatest  care  and  exactness  have  placed  the 
presence  of  ammonia  in  rain-water  beyond  all  doubt. 
It  has  hitherto  escaped  observation,  because  no  per- 
son thought  of  searching  for  it.*  All  the  rain-water 
employed  in  this  inquiry  was  collected  600  paces 
southwest  of  Giessen,  whilst  the  wind  was  blowing 
in  the  direction  of  the  town.  When  several  hundred 
pounds  'of  it  were  distilled  in  a  copper  still,  and  the 
first  two  or  three  pounds  evaporated  with  the  addi- 
tion of  a  little  muriatic  acid,  a  very  distinct  crystal- 
lization of  sal-ammoniac  was  obtained :  the  crystals 
had  always  a  brown  or  yellow  color. 

Ammonia  may  likewise  be  always  detected  in  snow- 
water. Crystals  of  sal-ammoniac  were  obtained  by 
evaporating  in  a  vessel  with  muriatic  acid  several 
pounds  of  snow,  which  were  gathered  from  the  sur- 
face of  the  ground  in  Marcl^  when  the  snow  had  a 
depth  of  10  inches.  Ammonia  was  set  free  from 
these  crystals  by  the  addition  of  hydrate  of  lime. 
The  inferior  layers  of  snow  which  rested  upon  the 
ground  contained  a  quantity  decidedly  greater  than 
those  which  formed  the  surface.f 

It  is  worthy  of  observation,  that  the  ammonia  con- 
tained in  rain  and  snow  water  possesses  an  offensive 
smell  of  perspiration  and  animal  excrements,  —  a 
fact  which  leaves  no  doubt  respecting  its  origin. 

not  be  too  distinctly  kept  in  mind  that  humic  acid  is  the  product  of  the 
decomposition  of  Awmw^,  by  means  of  caustic  alkalies.  Again,  if  the 
colored  solutions  of  humates  of  ammonia,  lime,  or  magnesia,  be  poured 
upon  good  mould  or  decayed  oak-wood  (which  is  nearly  pure  humus), 
and  allowed  to  filter,  the  solutions  are  observed  to  pass  through  quite 
colorless  ;  they  are  decolorized  just  as  if  they  had  been  filtered  through 
charcoal.  Here,  then,  humus  possesses  the  property  of  extracting  hu' 
mic  acid  from  water ;  or,  in  other  words,  soils  have  the  power  of  ren- 
dering humic  acid  insoluble,  or  unfit  for  assimilation.  —  Ep. 

*  It  has  been  discovered  by  Mr.  Hayes  in  rain-water  in  Vermont, 
—  and  in  hailstones  by  M.  Girardin,  see  London  and  Edinburgh  Philo- 
sophical Magazine,  1839,  Vol.  XV.  p.  252.     See  note  in  Appendix. 

t  Johnston  detected  it  in  snow  which  fell  at  Durham,  G.  B.,  by  add- 
ing two  drops  of  sulphuric  acid  to  four  pints  of  snow-water,  evaporating 
to  dryness,  and  mixing  the  dry  mass  with  quicklime  or  caustic  potash. 
The  residual  mass  contained  a  brown  organic  matter,  mixed  with  the 
sulphate  of  ammonia. 


92        SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

Hunefield  has  proved  that  all  the  springs  in  Greifs- 
walde,  Wick,  Eldena,  and  Kostenhagen,  contain  car- 
bonate and  nitrate  of  ammonia.  Ammoniacal  salts 
have  been  discovered  in  many  mineral  springs  in 
Kissingen  and  other  places.  The  ammonia  of  these 
salts  can  only  arise  from  the  atmosphere. 

Any  one  may  satisfy  himself  of  the  presence  of 
ammonia  in  rain  by  simply  adding  a  little  sulphuric 
or  muriatic  acid  to  a  quantity  of  rain-wafer,  and 
evaporating  this  nearly  to  dryness  in  a  clean  porce- 
lain basin.  The  ammonia  remains  in  the  residue,  in 
combination  with  the  acid  employed ;  and  may  be 
detected  either  by  the  addition  of  a  little  chloride 
of  platinum,  or  more  simply  by  a  little  powdered 
lime,  which  separates  the  ammonia,  and  thus  renders 
its  peculiar  pungent  smell  sensible.*  The  sensation 
which  is  perceived  upon  moistening  the  hand  with 
rain-water,  so  different^  from  that  produced  by  pure 
distilled  water,  and  to  which  the  term  softness  is 
vulgarly  applied,  is  also  due  to  the  carbonate  of 
ammonia  contained  in  the  former.f 

The  ammonia  which  is  removed  from  the  atmo- 
sphere by  rain  and  other  causes,  is  as  constantly  re- 
placed by  the  putrefaction  of  animal  and  vegetable 
matters.  A  certain  portion  of  that  which  falls  with 
the  rain  evaporates  again  with  the  water,  but  another 
portion  is,  we  suppose,  taken  up  by  the  roots  of 
plants,  and,  entering  into  new  combinations  in  the 
different  organs  of  assimilation,  produces  albumen, 
gluten,  quinine,  morphia,  cyanogen,  and  a  number 
of  other  compounds  containing  nitrogen.  The  chem- 
ical   characters   of   ammonia   render   it    capable    of 

*  Since  the  appearance  of  the  first  edition,  this  experiment  has  been 
repeated  by  many  in  France,  Germany,  America,  and  England,  and  the 
existence  of  ammonia  in  the  atmosphere  has  been  completely  confirm- 
ed. The  assertion,  that  this  ammonia  possesses  the  "offensive  smell 
of  perspiration  and  animal  excrements,"  has  been  ridiculed  by  many 
as  fanciful,  —  by  none,  however,  who  have  made  the  experiment.  The 
experiment  is  so  exceedingly  easy  to  perform,  that  any  one  may  con- 
vince himself  of  the  accuracy  of  the  statement.  —  Ed. 

t  A  small  quantity  of  ammonia  water,  added  to  what  is  commonly 
called  hard  water,  will  give  it  the  softness  of  rain  or  snow  water. 


EXISTENCE  OF  AMMONIA  IN  THE  JUICES  OF  PLANTS.         93 

entering  into  such  combinations,  and  of  undergoing 
numerous  transformations.  We  have  now  only  to 
consider  whether  it  really  is  taken  up  in  the  form 
of  ammonia  by  the  roots  of  plants,  and  in  that  form 
applied  by  their  organs  to  the  production  of  the 
azotized  matters  contained  in  them.  This  question 
is  susceptible  of  easy  solution  by  well-known  facts. 

In  the  year  1834,  I  was  engaged  with  Dr.  Wil- 
brand,  Professor  of  Botany  in  the  University  of 
Giessen,  in  an  investigation  respecting  the  quantity 
of  sugar  contained  in  different  varieties  of  maple- 
trees,  which  grew  upon  soils  which  were  not  ma- 
nured. We  obtained  crystallized  sugars  from  all, 
by  simply  evaporating  their  juices,  without  the  ad- 
dition of  any  foreign  substance  ;  and  we  unexpected- 
ly made  the  observation,  that  a  great  quantity  of 
ammonia  was  emitted  from  this  juice  when  mixed 
with  lime,  and  also  from  the  sugar  itself  during  its 
refinement.  The  vessels  which  hung  upon  the  trees 
in  order  to  collect  the  juice  were  watched  with 
greater  attention,  on  account  of  the  suspicion  that 
some  evil-disposed  persons  had  introduced  urine 
into  them,  but  still  a  large  quantity  of  ammonia  was 
again  found  in  the  form  of  neutral  salts.  The  juice 
had  no  color,  and  had  no  reaction  on  that  of  vegeta- 
bles. Similar  observations  were  made  upon  the 
juice  of  the  birch  tree ;  the  specimens  subjected  to 
experiment  were  taken  from  a  wood  several  miles 
distant  from  any  house,  and  yet  the  clarified  juice, 
evaporated  with  lime,  emitted  a  strong  odor  of 
ammonia. 

In  the  manufactories  of  beet-root  sugar,  many 
thousand  cubic  feet  of  juice  are  daily  purified  with 
lime,  in  order  to  free  it  from  vegetable  albumen  and 
gluten,  and  it  is  afterwards  evaporated  for  crystalli- 
zation. Every  person  who  has  entered  such  a  manu- 
factory must  have  been  astonished  at  the  great 
quantity  of  ammonia  which  is  volatilized  along  with 
the  steam.  This  ammonia  must  be  contained  in  the 
form  of  an    ammoniacal    salt,  because    the    neutral 


94  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

juice  possesses  the  same  characters  as  the  solution 
of  such  a  salt  in  water;  it  acquires,  namely,  an 
acid  reaction  during  evaporation,  in  consequence  of 
the  neutral  salt  being  converted  by  loss  of  ammonia 
into  an  acid  salt.  The  free  acid  which  is  thus 
formed  is  a  source  of  loss  to  the  manufacturers  of 
sugar  from  beet-root,  by  changing  a  part  of  the 
sugar  into  uncrystallizable  grape  sugar  and  syrup. 

The  products  of  the  distillation  of  flowers,  herbs, 
and  roots,  with  water,  and  all  extracts  of  plants 
made  for  medicinal  purposes,  contain  ammonia.  The 
unripe,  transparent,  and  gelatinous  pulp  of  the  al- 
mond and  peach  emit  much  ammonia  when  treated 
with  alkalies.  (Robiquet.)  The  juice  of  the  fresh 
tobacco  leaf  contains  ammoniacal  salts.  The  water 
which  exudes  from  a  cut  vine,  when  evaporated 
with  a  few  drops  of  muriatic  acid,  also  yields  a 
gummy,  deliquescent  mass,  which  evolves  much  am- 
monia on  the  addition  of  lime.  Ammonia  exists  in 
every  part  of  plants,  in  the  roots  (as  in  beet-root), 
in  the  stem  (of  the  maple-tree),  and  in  all  blossoms 
and  fruit  in  an  unripe  condition. 

The  juices  of  the  maple  and  birch  contain  both 
sugar  and  ammonia,  and  therefore  afford  all  the  con- 
ditions necessary  for  the  formation  of  the  azotized 
components  of  the  branches,  blossoms,  and  leaves, 
as  well  as  of  those  which  contain  no  azote  or  nitro- 
gen. In  proportion  as  the  development  of  those 
parts  advances,  the  ammonia  diminishes  in  quantity, 
and  when  they  are  fully  formed,  the  tree  yields  no 
more  juice. 

The  employment  of  animal  manure  in  the  cultiva- 
tion of  grain,  and  the  vegetables  which  serve  for 
fodder  to  cattle,  is  the  most  convincing  proof  that 
the  nitrogen  of  vegetables  is  derived  from  ammonia. 
The  quantity  of  gluten  in  wheat,  rye,  and  barley,  is 
very  different ;  these  kinds  of  grain  also,  even  when 
ripe,  contain  this  compound  of  nitrogen  in  very 
different  proportions.  Proust  found  French  wheat 
to  contain  12*5  per  cent,  of  gluten;  Vogel  found  that 


VARIABLE  QUANTITIES  OF  GLUTEN  IN  WHEAT.  95 

the  Bavarian  contained  24  per  cent. ;  Davy  obtained 
19  per  cent,  from  winter,  and  24  from  summer 
wheat;  from  Sicilian  21,  and  from  Barbary  wheat 
19  per  cent.  The  meal  of  Alsace  wheat  contains, 
according  to  Boussingault,  17*3  per  cent,  of  gluten; 
that  of  wheat  grown  in  the  "  Jardin  des  Plantes  " 
26-7,  and  that  of  winter  wheat  3*33  per  cent.  Such 
great  differences  must  be  owing  to  some  cause,  and 
this  we  find  in  the  different  methods  of  cultivation. 
An  increase  of  animal  manure  gives  rise  not  only 
to  an  increase  in  the  number  of  seeds,  but  also  to 
a  most  remarkable  difference  in  the  proportion  of 
the  substances  containing  nitrogen,  such  as  the 
gluten  which  they  contain. 

Animal  manure,  in  as  far  as  regards  the  assimila- 
tion of  nitrogen,  acts  only  by  the  formation  of  am- 
monia. One  hundred  parts  of  wheat  grown  on  a 
soil  manured  with  cow-dung  (a  manure  containing 
the  smallest  quantity  of  nitrogen),  afforded  only 
11-95  parts  of  gluten,  and  64*34  parts  of  amylin,  or 
starch;  whilst  the  same  quantity,  grown  on  a  soil 
manured  with  human  urine,  yielded  the  maximum  of 
gluten,  namely  35*1  per  cent.  Putrefied  urine  con- 
tains nitrogen  in  the  forms  of  carbonate,  phosphate, 
and  lactate  of  ammonia,  and  in  no  other  form  than 
that  of  ammoniacal  salts. 

"  Putrid  urine  is  employed  in  Flanders  as  a  ma- 
nure with  the  best  results.  During  the  putrefaction 
of  urine,  ammoniacal  salts  are  formed  in  large  quan- 
tity, it  may  be  said  exclusively;  for  under  the  in- 
fluence of  heat  and  moisture,  urea,  the  most  promi- 
nent ingredient  of  the  urine,  is  converted  into  car- 
bonate of  ammonia.  The  barren  soil  on  the  coast 
of  Peru  is  rendered  fertile  by  means  of  a  manure 
called  Guano,  which  is  collected  from  several  islands 
in  the  South  Sea.*  It  is  sufficient  to  add  a  small 
quantity  of  guano  to   a  soil,  which  consists  only  of 

*  The  guano,  which  forms  a  stratum  several  feet  in  thickness  upon 
the  surface  of  these  islands,  consists  of  the  putrid  excrements  of  in- 


96  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

sand  and  clay,  in  order  to  procure  the  richest  crop 
of  maize.  The  soil  itself  does  not  contain  the 
smallest  particle  of  organic  matter,  and  the  manure 
employed  is  formed  only  of  urate,  phosphate,  oxa- 
latej  and  carbonate  of  ammonia,  together  with  a  few 
earthy  salts.*" 

Ammonia,  therefore,  must  have  yielded  the  nitrogen 
to  these  plants.  Gluten  is  obtained  not  only  from 
corn,  but  also  from  grapes  and  other  plants  ;  but 
that  extracted  from  the  grapes  is  called  vegetable 
albumen,  although  it  is  identical  in  composition  and 
properties  with  the  ordinary  gluten. 

It  is  ammonia  which  yields  nitrogen  to  the  vege- 
table albumen,  the  principal  constituent  of  plants  ; 
and  it  must  be  ammonia  which  forms  the  red  and  blue 

numerable  sea  fowl  that  remain  on  them  during  the  breeding  season. 
(See  the  Chapter  on  Manures.) 

According  to  Fourcroy  and  Vauquelin  it  contains  a  fourth  part  of 
its  weight  of  uric  acid,  with  ammonia  and  potash. 

The  London  and  Edinburgh  Philosophical  Magazine,  for  July,  1841, 
contains  a  new  analysis  of  the  guano,  made  by  M.  Voelckel  in  the 
laboratory  of  Professor  Wohler,.  and  confirms  what  Klaproth  found, 
viz.,  that  it  contains,  besides  unchanged  uric  acid,  a  considerable  quan- 
tity of  two  of  its  usual  products  of  decomposition,  viz.  oxalic  acid  and 
ammonia.     100  parts  of  moist  guano,  contain, 

(Voelckel),  (Klaproth.) 

Urate  of  ammonia,  .        .        .         9.0  16.0 

Oxalate  of      do 10.6 

Do.     of  lime,      ....  7.0  12.75 

Phosphate  of  ammonia,  .  .  .  6.0 
Phosphate  of  ammonia  and  magnesia,  2.6 
Sulphate  of  potash,      ....     5.5 

Do.     of  soda,       ....         3.8  common  salt  0.05 
Chloride  of  ammonium,      .         .        .      4.2 
Phosphate  of  lime,  .        .        .       14.3  10.00 

Clay  and  sand,  ....      4.7  32.00 

Undetermined  organic  substances,"] 
of  which  about  12  per  cent,  is  sol-  (     32.3  28.75 

uble  in  water.     A  small  quantity  j 

of  a  soluble  salt  of  iron.     Water,  J 

lOO.O  99.55 

Mr.  J.  H.  Blake  of  Boston,  who  has  recently  visited  Peru,  informs 
me,  that  near  Pabellon  de  Pica  there  is  a  high  hill,  the  base  of  which, 
consisting  chiefly  of  guano,  is  washed  by  the  sea.  From  this  bed, 
which  is  nearly  a  mile  in  length,  and  from  800  to  900  feet  high,  guano 
might  be  obtained  at  a  cost,  which  would  probably  not  exceed  a  cent 
ana  a  half  per  pound,  delivered  in  the  United  States.  (See  also  Ap- 
pendix.) 
*  Boussingault.  Ann.  de  Ch.  et  de  Phys.  Ixv.  p.  319. 


COMPOSITION  OF  EXCREMENTITIOUS  MATTER.  97 

coloring  matters  of  flowers.  Nitrogen  is  not  pre- 
sented to  wild  plants  in  any  other  form  capable  of 
assimilation.  Ammonia,  by  its  transformation,  fur- 
nishes nitric  acid  to  the  tobacco  plant,  sun-flower, 
Chenopodium,  and  Borago  officinalis,  when  they  grow 
in  a  soil  completely  free  from  nitre.  Nitrates  are 
necessary  constituents  of  these  plants,  which  thrive 
only  when  ammonia  is  present  in  large  quantity,  and 
when  they  are  also  subject  to  the  influence  of  the 
direct  rays  of  the  sun,  an  influence  necessary  to 
effect  the  disengagement  within  their  stem  and 
leaves  of  the  oxygen,  which  shall  unite  with  the 
ammonia  to  form  nitric  acid. 

The  urine  of  men  and  of  carnivorous  animals 
contains  a  large  quantity  of  nitrogen,  partly  in  the 
form  of  phosphates,  partly  as  urea.  Urea  is  con- 
verted during  putrefaction  into  carbonate  of  ammo- 
nia, that  is  to  say,  it  takes  the  form  of  the  very  salt 
which  occurs  in  rain-water.  Human  urine  is  the 
most  powerful  manure  for  all  vegetables  containing 
nitrogen ;  that  of  horses  and  horned  cattle  contains 
less  of  this  element,  but  infinitely  more  than  the 
solid  excrements  of  these  animals.  In  addition  to 
urea,  the  urine  of  herbivorous  animals  contains  hip- 
puric  acid,*  which  is  decomposed  during  putrefaction 
into  benzoic  acidf  and  ammonia.  The  latter  enters 
into  the  composition  of  the  gluten,  but  the  benzoic 
acid  often  remains  unchanged :  for  example,  in  the 
Anthoxanthum  odoratum. 

The  solid  excrements  of  animals  contain  compar- 
atively very  little  nitrogen,  but  this  could  not  be 
otherwise.  The  food  taken  by  animals  supports 
them  only  in  so  far  as  it  offers  elements  for  assimila« 
tion  to  the  various   organs  which   they  may  require 

*  Rouelle  announced  the  discovery  of  an  acid  in  the  urine  of  the 
horse,  which  he  called  henzoic^hni  in  1834  Liebig  showed  that  this  was 
not  benzoic  acid,  but  one  easily  convertible  into  it,  and  distinguished  it 
by  the  name  hippuriCj  from  Xnnog^  a  horse,  and  ovqov,  urine. 

t  Benzoic  acid  exists  in  gum  benzoin,  &c. ;  it  is  formed,  according 
to  Liebig,  by  the  oxidation  of  a  supposed  base  called  benzule.  Its 
composition  is  carbon  14,  hydrogen  5,  oxygen  2. 

9 


98  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

for  their  increase  or  renewal.  Corn,  grass,  and  all 
plants,  without  exception,  contain  azotized  substan- 
ces.* The  quantity  of  food  which  animals  take  for 
their  nourishment,  diminishes  or  increases  in  the 
same  proportion  as  it  contains  more  or  less  of  the 
substances  containing  nitrogen.  A  horse  may  be 
kept  alive  by  feeding  it  with  potatoes,  which  contain 
a  very  small  quantity  of  nitrogen ;  but  life  thus 
supported  is  a  gradual  starvation ;  the  animal  in- 
creases neither  in  size  nor  strength,  and  sinks  under 
every  exertion.  The  quantity  of  rice  which  an 
Indian  eats  astonishes  the  European ;  but  the  fact 
that  rice  contains  less  nitrogen  than  any  other  kind 
of  grain  at  once  explains  the  circumstance.f 

Now,  as  it  is  evident  that  the  nitrogen  of  the 
plants  and  seeds  used  by  animals  as  food  must  be 
employed  in  the  process  of  assimilation,  it  is  natural 
to  expect  that  the  excrements  of  these  animals  will 
be  deprived  of  it  in  proportion  to  the  perfect  diges- 
tion of  the  food,  and  can  only  contain  it  when  mixed 
with  secretions  from  the  liver  and  intestines.  Under 
all  circumstances,  they  must  contain  less  nitrogen 
than  the  food.  When,  therefore,  a  field  is  manured 
with  animal  excrements,  a  smaller  quantity  of  matter 

*  The  late  Professor  Gorham  obtained  from  Indian  corn  a  substance 
to  which  he  gave  the  name  Zeine,  according  to  whose  analysis  it  con- 
tains no  nitrogen ;  but  ammonia  has  since  been  obtained  from  it. 

t  According  to  the  analysis  of  Braconnot  {<^nn.  de  Chim.  et  de  Phys. 
t.  iv.  p.  370),  this  grain  is  thus  constituted. 

Carolina  rice.  Piedmont  rice. 

Water,  .        .        .        5.00  7.00 

Starch,     ....    85.07  83.80 

Parenchyma,      .        .        .    4.80  4.80 

Gluten,  .        .        .        3.60  3.60 

Uncrystallizable  sugar,  0.29  0.05 

Gummy  matter  approach-  ^   q  71  n  10 

inff  to  starch,  ) 

Oil,         ....        0.13  0.25 

Phosphate  of  lime,    .        .    0.13  0.40 

99.73  100.00.  With  tra- 

ces of  muriate  of  potash,  phosphate  of  potash,  acetic  acid,  sulphur, 
and  lime,  and  potash  united  to  a  vegetable  alkali. 

Vauquelin  was  unable  to  detect  any  saccharine  matter  in  rice,  — 
Thomson's  Organic  Chemistry,  p.  883. 


FORM  IN  WHICH  AMMONIA  IS  PRESENTED.  99 

containing  nitrogen  is  added  to  it  than  has  been 
taken  from  it  in  the  form  of  grass,  herbs,  or  seeds. 
By  means  of  manure,  an  addition  only  is  made  to 
the  nourishment  which  the  air  supplies. 

In  a  scientific  point  of  view,  it  should  be  the  care 
of  the  agriculturist  so  to  employ  all  the  substances 
containing  a  large  proportion  of  nitrogen  which  his 
farm  affords  in  the  form  of  animal  excrements,  that 
they  shall  serve  as  nutriment  to  his  own  plants. 
This  will  not  be  the  case  unless  those  substances 
are  properly  distributed  vpon  his  land.  A  heap  of 
manure  lying  unemployed  upon  his  land  would  serve 
him  no  more  than  his  neighbors.  The  nitrogen  in 
it  would  escape  as  carbonate  of  ammonia  into  the 
atmosphere,  and  a  mere  carbonaceous  residue  of 
decayed  plants  would,  after  some  years,  be  found  in 
its  place. 

All  animal  excrements  emit  carbonic  acid  and 
ammonia,  as  long  as  nitrogen  exists  in  them.  In 
every  stage  of  their  putrefaction  an  escape  of  am- 
monia from  them  may  be  induced  by  moistening  them 
with  a  potash  ley;  the  ammonia  being  apparent  to 
the  senses  by  a  peculiar  smell,  and  by  the  dense 
white  vapor  which  arises  when  a  solid  body  moist- 
ened with  an  acid  is  brought  near  it.  This  ammonia 
evolved  from  manure  is  imbibed  by  the  soil  either 
in  solution  in  water,  or  in  the  gaseous  form,  and 
plants  thus  receive  a  larger  supply  of  nitrogen  than 
is  afforded  to  them  by  the  atmosphere. 

But  it  is  much  less  the  quantity  of  ammonia, 
yielded  to  a  soil  by  animal  excrements,  than  the 
form  in  which  it  is  presented  by  them,  that  causes 
their  great  influence  on  its  fertility.  Wild  plants 
obtain  more  nitrogen  from  the  atmosphere  in  the 
form  of  ammonia  than  they  require  for  their  growth, 
for  the  water  which  evaporates  through  their  leaves 
and  blossoms,  emits,  aft^r  some  time,  a  putrid  smell, 
a  peculiarity  possessed  only  by  such  bodies  as  con- 
tain nitrogen.  Cultivated  plants  receive  the  same 
quantity  of  nitrogen  from   the  atmosphere   as  trees, 


100  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

shrubs,  and  other  wild  plants;  but  this  is  not  suffi- 
cient for  the  purposes  of  agriculture.  Agriculture 
differs  essentially  from  the  cultivation  of  forests, 
inasmuch  as  its  principal  object  consists  in  the  pro- 
duction of  nitrogen  under  any  form  capable  of 
assimilation;  whilst  the  object  of  forest  culture  is 
confined  principally  to  the  production  of  carbon. 
All  the  various  means  of  culture  are  subservient  to 
these  two  main  purposes.  A  part  only  of  the  carbonate 
of  ammonia  which  is  conveyed  by  rain  to  the  soil  is 
received  by  plants,  becausp  a  certain  quantity  of  it 
is  volatilized  with  the  vapor  of  water;  only  that 
portion  of  it  can  be  assimilated  which  sinks  deeply 
into  the  soil,  or  which  is  conveyed  directly  to  the 
leaves  by  dew,  or  is  absorbed  from  the  air  along 
with  the  carbonic  acid. 

Liquid  animal  excrements,  such  as  the  urine  with 
which  the  solid  excrements  are  impregnated,  contain 
the  greatest  part  of  their  ammonia  in  the  state  of 
salts,  in  a  form,  therefore,  in  which  it  has  completely 
lost  its  volatility ;  when  presented  in  this  condition, 
not  the  smallest  portion  of  the  ammonia  is  lost  to 
the  plants ;  it  is  all  dissolved  by  water,  and  imbibed 
by  their  roots.  The  evident  influence  of  gypsum 
upon  the  growth  of  grasses  —  the  striking  fertility 
and  luxuriance  of  a  meadow  upon  which  it  is  strewed 
—  depends  only  upon  its  fixing  in  the  soil  the  am- 
monia of  the  atmosphere,  which  would  otherwise  be 
volatilized,  with  the  water  which  evaporates.*  The 
carbonate  of  ammonia  contained  in  rain-water  is 
decomposed  by  gypsum,  in  precisely  the  same  man- 
ner as  in  the  manufacture  of  sal-ammoniac.  Soluble 
sulphate  of  ammonia  and  carbonate  of  lime  are 
formed ;  and  this  salt  of  ammonia  possessing  no 
volatility  is  consequently  retained  in  the  soil.  All 
the  gypsum  gradually  disappears,  but  its  action  upon 
,—. — _ —  » 

*  It  has  long  been  the  practice  in  some  parts  of  the  country  to  strew 
the  floors  of  stables  with  gypsum.  This  prevents  the  disagreeable  odor 
arising  from  the  putrefaction  of  stable  manure,  by  decomposing  the 
ammoniacal  salts  which  are  formed. —  Ed. 


USE  OF  GYPSUM.  IQl 

''  the  carbonate  of  ammonia  continues  as  long  as  a 
trace  of  it  exists. 

The  beneficial  influence  of  gypsum  and  of  many- 
other  salts  has  been  compared  to  that  of  aroraatics, 
which  increase  the  activity  of  the  human  stomach 
and  intestines,  and  give  a  tone  to  the  whole  system. 
But  plants  contain  no  nerves ;  we  know  of  no  sub- 
stance capable  of  exciting  them  to  intoxication  and 
madness,  or  of  lulling  them  to  sleep  and  repose. 
No  substance  can  possibly  cause  their  leaves  to  ap- 
propriate a  greater  quantity  of  carbon  from  the 
atmosphere,  when  the  other  constituents  which  the 
seeds,  roots,  and  leaves  require  for  their  growth  are 
wanting.*  The  favorable  action  of  small  quantities 
of  aromatics  upon  man,  when  mixed  with  his  food, 
is  undeniable ;  but  aromatics  are  given  to  plants 
without  food  to  be  digested,  and  still  they  flourish 
with  greater  luxuriance. 

It  is  quite  evident,  therefore,  that  the  common 
view  concerning  the  influence  of  certain  salts  upon 
the  growth  of  plants  evinces  only  ignorance  of  its 
cause. 

The  action  of  gypsum  or  chloride  of  calcium  really 
consists  in  their  giving  a  fixed  condition  to  the 
nitrogen  —  or  ammonia  which  is  brought  into  the 
soil,  and  which  is  indispensable  for  the  nutrition  of 
plants. 

In  order   to  form   a  conception  of  the   effect   of 

*  In  1831, 1  suggested  to  a  well  known  and  most  successful  culti- 
vator (Mr.  Haggerston),  the  application  of  a  weak  solution  of  chlorine 
gas  to  the  soil  in  which  plants  were  growing.  It  appeared  to  act 
merely  as  a  stimulant,  the  plants  flourished  for  a  time  with  great  lux- 
uriance, and  in  some  the  foliage  was  remarkable.  The  leaves  of  a 
Pelargonium  (well  known  as  the  Washington  Geranium)  attained  the 
diameter  of  a  foot,  but  the  flowers  were  by  no  means  equal  to  those 
of  similar  plants  cultivated  in  the  usual  manner;  the  plants  soon 
perished.  Probably  a  supply  of  nutriment  proportioned  to  the  increased 
demand  was  not  supplied. 

The  necessity  for  this  supply  is  now  well  known,  and  Pelargoniums 
are  now  grown  with  great  luxuriance  and  perfection,  both  of  leaves 
and  flowers,  by  the  free  use  of  "  manure  water,"  obtained  by  steeping 
horsedung  in  rain-water.  The  soil,  too,  best  adapted  to  the  plants  is 
chiefly  prepared  from  decayed  vegetable  matter,  derived  from  decom- 
posed leaves  and  plants,  mixed  with  that  from  the  sods  of  fields. 

9* 


102  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

gypsum,  it  may  be  sufficient  to  remark,  that  110  lbs. 
of  burned  gypsum  fixes  as  much  ammonia  in  the 
soil  as  6887  lbs.  of  horse's  urine*  would  yield  to  it, 
even  on  the  supposition  that  all  the  nitrogen  of  the 
urea  and  hippuric  acid  were  absorbed  by  the  plants 
without  the  smallest  loss,  in  the  form  of  carbonate 
of  ammonia.  If  we  admit  with  Boussingaultf  that 
the  nitrogen  in  grass  amounts  to  ^Jq  of  its  weight, 
then  every  pound  of  nitrogen  which  we  add  in- 
creases the  produce  of  the  meadow  110  lbs.,  and 
this  increased  produce  of  110  lbs.  is  effected  by  the 
aid  of  a  little  more  than  4  lbs.  of  gypsum. 

Water  is  absolutely  necessary  to  effect  the  decom- 
position of  the  gypsum,  on  account  of  its  difficult 
solubility,  (1  part  of  gypsum  requires  400  parts  of 
water  for  solution,)  and  also  to  assist  in  the  absorp- 
tion of  the  sulphate  of  ammonia  by  the  plants : 
hence  it  happens,  that  the  influence  of  gypsum  is 
not  observable  on  dry  fields  and  meadows.  In  such 
it  would  be  advisable  to  employ  a  salt  of  more  easy 
solubility,  such  as  chloride  of  calcium. 

The  decomposition  of  gypsum  by  carbonate  of 
ammonia  does  not  take  place  instantaneously;  on 
the  contrary,  it  proceeds  very  gradually,  and  this 
explains  why  the  action  of  the  gypsum  lasts  for 
several  years. 

The  advantage  of  manuring  fields  with  burned 
clay,  and  the  fertility  of  ferruginous  soils,  which 
have  been  considered  as  facts  so  incomprehensible, 
may  be  explained  in  an  equally  simple  manner. 
They  have  been  ascribed  to  the  great  attraction  for 
water,  exerted  by  dry  clay  and  ferruginous  earth; 
but  common  dry  arable  land  possesses  this  property 

*  The  urine  of  the  horse  contains,  according  to  Fourcroy  and  Vau- 
quelin,  in  1000  parts, 

Urea  ...         7  parts. 

Hippurate  of  soda    .      .    24    " 
Salts  and  water    .       .      979    " 


1000  parts, 
t  Boussingault,  ^nn.  de  Ch.  et  de  Phys.,  t.  Ixiii.  page  243. 


USE  OF  BURNED  CLAY  AS  A  MANURE.         103 

in  as  great  a  degree :  and  bedsides,  what  influence 
can  be  ascribed  to  a  hundred  pounds  of  water  spread 
over  an  acre  of  land,  in  a  condition  in  which  it  can- 
not be  serviceable  either  by  the  roots  or  leaves  1 
The  true  cause  is  this :  — 

The  oxides  of  iron  and  alumina  are  distinguished 
from  all  other  metallic  oxides  by  their  power  of  form- 
ing solid  compounds  with  ammonia.  The  precipi- 
tates obtained  by  the  addition  of  ammonia  to  salts 
of  alumina  or  iron  are  true  salts,  in  which  the  ammo- 
nia is  contained  as  a  base.  Minerals  containing  alu- 
mina or  oxide  of  iron  also  possess,  in  an  eminent  de- 
gree, the  remarkable  property  of  attracting  ammonia 
from  the  atmosphere  and  of  retaining  it.  Vauquelin, 
whilst  engaged  in  the  trial  of  a  criminal  case,  discov- 
ered that  all  rust  of  iron  contains  a  certain  quantity  of 
ammonia.  Chevalier  afterwards  found  that  ammonia 
is  a  constituent  of  all  minerals  containing  iron ;  that 
even  hematite,  a  mineral  which  is  not  at  all  porous, 
contains  one  per  cent,  of  it.  Bonis  showed  also,  that 
the  peculiar  odor  observed  on  moistening  minerals 
containing  alumina,  is  partly  owing  to  their  exhaling 
ammonia.  Indeed,  gypsum  and  some  varieties  of 
alumina,  pipe-clay  for  example,  emit  so  much  ammo- 
nia, when  moistened  with  caustic  potash,  that  even 
after  they  have  been  exposed  for  two  days,  reddened 
litmus  paper  held  over  them  becomes  blue.  Soils, 
therefore,  which  contain  oxides  of  iron,  and  burned 
clay,  must  absorb  ammonia,  an  action  which  is  fa- 
vored by  their  porous  condition  ;  they  further  pre- 
vent the  escape  of  the  ammonia  once  absorbed,  by 
their  chemical  properties.  Such  'soils,  in  fact,  act 
precisely  as  a  mineral  acid  woufd  do,  if  extensively 
spread  over  their  surface;  with  this  difference,  that 
the  acid  would  penetrate  the  ground,  enter  into  com- 
bination with  lime,  alumina,  and  other  bases,  and 
thus  lose,  in  a  few  hours,  its  property  of  absorbing 
ammonia  from  the  atmosphere.  The  addition  of 
burned  clay  to  soils  has  also  a  secondary  influence ; 


104  SOURCE  AND  ASSIMILATION  OF  NITROGEN. 

it  renders  the  soil  porous,  and,  therefore,  more  per- 
meable to  air  and  moisture. 

The  ammonia  absorbed  by  the  clay  or  ferruginous 
oxides  is  separated  by  every  shower  of  rain,  and 
conveyed  in  solution  to  the  soil. 

Powdered  charcoal  possesses  a  similar  action,  but 
surpasses  all  other  substances  in  the  power  which  it 
possesses  of  condensing  ammonia  within  its  pores, 
particularly  when  it  has  been  previously  heated  to 
redness.  Charcoal  absorbs  90  times  its  volume  of 
ammoniacal  gas,  which  may  be  again  separated  by 
simply  moistening  it  with  water.  (De  Saussure.) 
Decayed  wood  approaches  very  nearly  to  charcoal  in 
this  power ;  decayed  oak  wood  absorbs  72  times  its 
volume,  after  having  been  completely  dried  under 
the  air-pump.*  We  have  here  an  easy  and  satisfac- 
tory means  of  explaining  still  further  the  properties 
of  humus,  or  wood  in  a  decaying  state.  It  is  not 
only  a  slow  and  constant  source  of  carbonic  acid, 
but  it  is  also  a  means  by  which  the  necessary  nitro- 
gen is  conveyed  to  plants. 

Nitrogen  is  found  in  lichens,  which  grow  on  basal- 
tic rocks.  Our  fields  produce  more  of  it  than  we 
have  given  them  as  manure,  and  it  exists  in  all  kinds 
of  soils  and  minerals  which  were  never  in  contact 
with  organic  substances.  The  nitrogen  in  these  cases 
could  only  have  been  extracted  from  the  atmosphere. 

We  find  this  nitrogen  in  the  atmosphere  in  rain 
water  and  in  all  kinds  of  soils,  in  the  form  of  ammo- 
nia, as  a  product  of  the  decay  and  putrefaction  of 
preceding  generations  of  animals  and  vegetables. 
We  find  likewise  that  the  proportion  of  azotized  mat- 
ters in  plants  is  augmented  by  giving  them  a  larger 
supply  of  ammonia  conveyed  in  the  form  of  animal 
manure. 

No  conclusion  can  then  have  a  better  foundation 

*  In  experiments  instituted  by  Dr.  Daubeny,  with  a  view  of  ascer- 
taining whether  vegetable  mould  had  not  the  same  property,  he  found 
that  both  carbonic  acid  and  ammoniacal  gases  were  condensed  within 
its  pores,  as  they  would  be  by  a  lump  of  charcoal. 


OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS.  105 

than  this,  that  it  is  the  ammonia  of  the  atmosphere 
(^hich  furnishes  nitrogen  to  plants.* 
Carbonic  acid,  water,  and  ammonia,  contain  the 
elements  necessary  for  the  suj^port  of  animals  and 
vegetables.  The  same  substances  are  the  ultimate 
products  of  the  chemical  processes  of  decay  and  pu- 
trefaction. All  the  innumerable  products  of  vitality 
resume,  after  death,  the  original  form  from  which 
they  sprung.  And  thus  death,  - —  the  complete  dis- 
solution of  an  existing  generation,  —  becomes  the 
source  of  life  for  a  new  one. 


CHAPTER  VI. 

OF  THE  INORGANIC   CONSTITUENTS  OF  PLANTS. 

Carbonic  acid,  water,  and  ammonia,  are  necessary 
for  the  existence  of  plants,  because  they  contain  the 
elements  from  which  their  organs  are  formed;  but 
other  substances  are  likewise  requisite  for  the  for- 
mation of  certain  organs  destined  for  special  func- 
tions peculiar  to  each  family  of  plants.  Plants  ob- 
tain these  substances  from  inorganic  nature.  In  the 
ashes  left  after  the  incineration  of  plants,  the  same 
substances  are  found,  although  in  a  changed  con- 
dition. 

Although  the  vital  principle  exercises  a  great  pow- 
er over  chemical  forces,  yet  it  does  so  only  by  direct- 
ing the  way  in  which  they  are  to  act,  and  not  by 
changing  the  laws  to  which  they  are  subject.  Hence 
when  the  chemical  forces  are  employed  in  the  pro- 
cesses of  vegetable  nutrition,  they  must  produce  the 
same  results  which  are  observed  in  ordinary  chemical 
phenomena.  The  inorganic  matter  contained  in  plants 

*  From  some  experiments  with  respect  to  the  action  of  light  upon 
plants,  Dr.  Daubeny  is  inclined  to  suspect  that  in  some  cases  hydro- 
gen is  assimilated  whilst  nitroo-en  is  disengaged.  See  his  Memoir  in 
Philos.  Trans.  1836. 


106  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 


must,  therefore,  be  subordinate  to  the  laws  which 
regulate  its  combinations  in  common  chemical  pro- 
cesses. 

The  most  importaift  division  of  inorganic  substan- 
ces is  that  of  acids  and  alkalies.  Both  of  these  have 
a  tendency  to  unite  together,  and  form  neutral  com- 
pounds, which  are  termed  salts.  According  to  the 
doctrine  of  equivalents,  these  combinations  are  al- 
ways effected  in  definite  proportions,  that  is  to  say, 
one  equivalent  of  an  acid  always  unites  with  one  or 
two  equivalents  of  a  base,  whatever  that  base  may 
be.  Thus  501*17  parts  by  weight  of  sulphuric  acid 
unite  with  1  eq.  of  potash,  and  form  1  eq.  of  sulphate 
of  potash ;  the  same  quantity  unites  with  1  eq.  of 
soda,  and  produces  sulphate  of  soda.  From  this 
fact  follows  the  rule,  —  that  the  quantity,  which  an 
acid  requires  of  an  alkali  for  its  saturation,  may  be 
represented  by  a  very  simple  number. 

It  is  perfectly  necessary  to  form  a  proper  concep- 
tion of  what  chemists  denominate  the  "  capacity 
for  saturation  of  an  acid,"  before  we  are  able  to 
form  a  correct  idea  of  the  functions  performed  in 
plants,  by  their  inorganic  constituents.  The  power 
of  a  base  to  neutralize  an  acid  does  not  depend 
upon  the  quantity  of  radical  which  it  contains,  but 
altogether  upon  the  quantity  of  its  oxygen.  Thus 
protoxide  of  iron  contains  1  eq.  of  oxygen,  and 
unites  with  1  eq.  of  sulphuric  acid  in  forming  a 
neutral  salt ;  but  peroxide  of  iron  contains  3  eq.  of 
oxygen,  and  requires  3  eq.  of  the  same  acid  for  its 
neutralization.  Hence  when  a  given  weight  of  an 
acid  is  neutralized  by  different  bases,  the  quantity 
of  oxygen  contained  in  these  bases  must  be  the 
same  as  is  exhibited  by  the  following  scale :  — 

501*17  parts  of  Sulphuric  Acid  neutralize  258-35  Magnesia        Oxygen  =  100 
"  "  "  647-29  Strontia  "       =100 

"  "  "  1451-61  Oxide  of  Silver  "       =100 

«  "  "  956-8    Barytes  «       =100 

It  follows  from  the  law  of  equivalents,  that  the 
quantity  of  oxygen  in  a  base  must  stand  in  a  simple 
relation  to  the  quantity  of  oxygen  in  an  acid  which 


IMPORTANCE  OF  ALKALINE  BASES.  *  107 

unites  with  it.  By  this  is  meant,  that  the  quantities 
in  both  cases  must  either  be  equal  or  multiples  of 
each  other  -,  for  the  doctrine  of  equivalents  denies 
the  possibility  of  their  uniting  in  fractional  parts. 
This  will  be  rendered  obvious  by  a  consideration  of 
the  two  following  examples : 

100  parts  of  Cyanic  Acid  contain  23  26  oxygen  =  1. 

100  parts  of  Cyanic  Acid  saturate  137-21  parts  of  potash,  which  contain 

23  26  oxygen  =  1 . 
100  parts  of  Nitric  Acid  contain  73-85  oxygen  =  5. 
100  parts  of  Nitric  Acid  saturate  214-40  parts  of  oxide  of  silver,  which 

contain  14  77  oxygen  =  1. 

In  the  first  of  these  cases,  the  relation  of  the 
oxygen  of  the  base  to  that  of  the  acid  is  as  1 :  1;  in 
the  second,  as  1 :  5.  The  capacity  for  saturation 
of  each  acid  is,  therefore,  the  constant  quantity  of 
oxygen  necessary  to  neutralize  100  parts  of  it. 

Many  of  the  inorganic  constituents  vary  accord- 
ing to  the  soil  in  which  the  plants  grow,  but  a  cer- 
tain number  of  them  are  indispensable  to  their  de- 
velopment. All  substances  in  solution  in  a  soil 
are  absorbed  by  the  roots  of  plants,  exactly  as  a 
sponge  imbibes  a  liquid,  and  all  that  it  contains, 
without  selection.  The  substances  thus  conveyed 
to  plants  are  retained  in  greater  or  less  quantity,  or 
are  entirely  separated  when  not  suited  for  assimi- 
lation. 

Phosphate  of  magnesia  in  combination  with  am- 
monia is  an  invariable  constituent  of  the  seeds  of 
all  kinds  of  grasses.  It  is  contained  in  the  outer 
horny  husk,  and  is  introduced  into  bread  along  with 
the  flour,  and  also  into  beer.  The  bran  of  flour  con- 
tains the  greatest  quantity  of  it.  It  is  this  salt 
which  forms  large  crystalline  concretions,  often 
amounting  to  several  pounds  in  weight,  in  the  ccBCum 
of  horses  belonging  to  millers ;  and  when  ammonia 
is  mixed  with  beer,  the  same  salt  separates  as  a 
white  precipitate. 

Most  plants,  perhaps  all  of  them,  contain  organic 
acids  of  very  different  composition  and  properties, 
all  of  which  are  in  combination  with  bases,  such  as 


108  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

potash,  soda,  lime,  or  magnesia.  These  bases  evi- 
dently regulate  the  formation  of  the  acids,  for  the 
diminution  of  the  one  is  followed  by  a  decrease  of 
the  other :  thus  in  the  grape,  for  example,  the  quan- 
tity of  potash  contained  in  its  juice  is  less  when 
it  is  ripe  than  when  unripe ;  and  the  acids,  under 
the  same  circumstances,  are  found  to  vary  in  a  simi- 
lar manner.  Such  constituents  exist  in  small  quan- 
tity in  those  parts  of  a  plant  in  which  the  process 
of  assimilation  is  most  active,  as  in  the  mass  of 
woody  fibre ;  and  their  quantity  is  greater  in  those 
organs  whose  office  it  is  to  prepare  substances  con- 
veyed to  them  for  assimilation  by  other  parts.  The 
leaves  contain  more  inorganic  matters  than  the 
branches,  and  the  branches  more  than  the  stem. 
The  potato  plant  contains  more  potash  before  blos- 
soming than  after  it. 

The  acids  found  in  the  different  families  of  plants 
are  of  various  kinds ;  it  cannot  be  supposed  that 
their  presence  and  peculiarities  are  the  result  of 
accident.  The  fumaric  and  oxalic  acids  in  the  liver- 
wort, the  kinovic  acid  in  the  China  nova,  the  ro- 
cellic  acid  in  the  Rocella  tinctoria,  the  tartaric  acid 
in  grapes,  and  the  numerous  other  organic  acids, 
must  serve  some  end  in  vegetable  life.  But  if  these 
acids  constantly  exist  in  vegetables,  and  are  neces- 
sary to  their  life,  which  is  incontestable,  it  is  equally 
certain  that  some  alkaline  base  is  also  indispensable, 
in  order  to  enter  into  combination  with  the  acids 
which  are  always  found  in  the  state  of  salts.  All 
plants  yield  by  incineration  ashes  containing  car- 
bonic acid ;  all  therefore  must  contain  salts  of  an 
organic  acid.* 

Now,  as  we  know  the  capacity  of  saturation  of 
organic  acids  to  be  unchanging,  it  follows  that  the 
quantity  of  the  bases  united  with  them  cannot  vary, 
and  for  this  reason  the  latter  substances  ought  to 

*  Salts  of  organic  acids  yield  carbonates  on  incineration,  if  they 
contain  either  alkaline  or  earthy  bases. 


INVARIABLE  QUANTITY  OF  ALKALINE  BASES.  109 

be  considered  with  the  strictest  attention  both  by 
the  agriculturist  and  physiologist. 

We  have  no  reason  to  believe  that  a  plant  in  a 
condition  of  free  and  unimpeded  growth  produces 
more  of  its  peculiar  acids  than  it  requires  for  its 
own  existence;  hence,  a  plant,  on  whatever  soil  it 
grows,  must  contain  an  invariable  quantity  of  alka- 
line bases.  Culture  alone  will  be  able  to  cause  a 
deviation. 

In  order  to  understand  this  subject  clearly,  it  will 
be  necessary  to  bear  in  mind  that  any  one  of  the 
alkaline  bases  may  be  substituted  for  another,  the 
action  of  all  being  the  same.  Our  conclusion  is 
therefore  by  no  means  endangered  by  the  existence 
of  a  particular  alkali  in  one  plant,  which  may  be 
absent  in  others  of  the  same  species.  If  this  in- 
ference be  correct,  the  absent  alkali  or  earth  must 
be  supplied  by  one  similar  in  its  mode  of  action,  or 
in  other  words,  by  an  equivalent  of  another  base. 
The  number  of  equivalents  of  these  various  bases 
which  may  be  combined  with  a  certain  portion  of 
acid  m\ist  necessarily  be  the  same,  and  therefore  the 
amount  of  oxygen  contained  in  them  must  remain 
unchanged  under  all  circumstances  and  on  whatever 
soil  they  grow. 

Of  course,  this  argument  refers  only  to  those 
alkaline  bases  which  in  the  form  of  organic  salts 
form  constituents  of  the  plants.  Now,  these  salts 
are  preserved  in  the  ashes  of  plants  as  carbonates, 
the  quantity  of  which  can  be  easily  ascertained. 

It  has  been  distinctly  shown,  by  the  analysis  of 
De  Saussure  and  Berthier,  that  the  nature  of  a  soil 
exercises  a  decided  influence  on  the  quantity  of  the 
different  metallic  oxides  contained  in  the  plants 
which  grow  on  it ;  that  magnesia,  for  example,  was 
contained  in  the  ashes  of  a  pine-tree  grown  at  Mont 
Breven,  whilst  it  was  absent  from  the  ashes  of  a 
tree  of  the  same  species  from  Mont  La  Salle,  and 
that  even  the  proportion  of  lime  and  potash  was 
very  different. 

10 


110  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

Hence  it  has  been  concluded,  (erroneously,  I  be- 
lieve,) that  the  presence  of  bases  exercises  no  par- 
ticular influence  upon  the  growth  of  plants :  but 
even  were  this  view  correct,  it  must  be  considered 
as  a  most  remarkable  accident  that  these  same 
analyses  furnish  proof  for  the  very  opposite  opinion. 
For  although  the  composition  of  the  ashes  of  these 
pine-trees  was  so  very  different,  they  contained, 
according  to  the  analyses  of  De  Saussure,  an  equal 
number  of  equivalents  of  metallic  oxides ;  or,  what 
is  the  same  thing,  the  quantity  of  oxygen  contained 
in  all  the  bases  was  in  both  cases  the  same. 

100  parts  of  the  ashes  of  the  pine-tree  from  Mont 
Breven  contained  — 

Carbonate  of  Potash    .    3*60  Quantity  of  oxygen  in  the  Potash       0*41 
''  Lime      .  4634  "  "  "      Lime         7-33 

"  Magnesia  6-77  "  «  «       Magnesia  1-27 

Sum  of  the  carbonates    56*71        Sum  of  the  oxygen  in  the  bases  9*01 

100  parts  of  the  ashes  of  the  pine  from  Mont  La 
Salle  contained* — 

Carbonate  of  Potash    .    7*36  Quantity  of  oxygen  in  the  Potash      0.85 
"  Lime      .  5119  «  "  "        Lime        810 

"  Magnesia  00-00 


Sum  of  the  carbonates  58-55        Sum  of  the  oxygen  in  the  bases    8-95 

The  numbers  9*01  and  8*95  resemble  each  other 
as  nearly  as  could  be  expected  even  in  analyses 
made  for  the  very  purpose  of  ascertaining  the  fact 
above  demonstrated,  which  the  analyst  in  this  case 
had  not  in  view. 

Let  us  now  compare  Berthier's  analyses  of  the 
ashes  of  tw^o  fir-trees,  one  of  which  grew  in  Norway, 
the  other  in  Allevard  (department  de  I'Isere).  One 
contained  50,  the  other  25  per  cent,  of  soluble  salts. 
A  greater  difference  in  the  proportion  of  the  alkaline 
bases   could  scarcely  exist  between  two  totally  dif- 

*  According  to  the  experiments  of  Saussure,  1000  parts  of  the  wood  of 
the  pine  from  Mont  Breven  gave  11*87  parts  of  ashes;  the  same  quan- 
tity of  wood  from  Mont  La  Salle  yielded  11-28  parts.  From  this  we 
might  conclude  that  the  two  pines,  although  brought  up  in  different 
soils,  yet  contained  the  same  quantity  of  inorganic  elements. 


INVARIABLE  QUANTITY  OF  ALKALINE  BASES.  HI 

ferent  plants,  and    yet   even  here    the   quantity  of 
oxygen  in  the  bases  of  both  was  the  same. 

100  parts  of  the  ashes  of  firwood  from  Allevard 
contained,  according  to  Berthier,  (Ann.  de  Chim.  et 
de  Phys.  t.  xxxii.  p.  248,) 

Potash  and  Soda  16*8  in  which  3*42  parts  must  be  oxygen. 
Lime  .        29-5        "        8-20    "  " 

Magnesia    .  3-2        "         1.20    "  «' 

49-5  12-82 

Only  part  of  the  potash  and  soda  in  these  ashes 
was  in  combination  with  organic  acids  ;  the  remain- 
der was  in  the  form  of  sulphates,  phosphates,  and 
chlorides.  One  hundred  parts  of  the  ashes  contain 
3*1  sulphuric  acid,  4-2  phosphoric  acid,  and  0*3  hy- 
drochloric acid,  which  together  neutralize  a  quantity 
of  base  containing  1*20  oxygen.  This  number  there- 
fore must  be  subtracted  from  12-82.  The  remainder 
11*62  indicates  the  quantity  of  oxygen  in  the  alka- 
line bases,  combined  with  organic  acids  in  the  fir- 
wood  of  Allevard. 

The  firwood  of  Norway  contained  in  100  parts,^ — 

Potash  .  14-1  of  which  2-4  parts  would  be  oxygen. 

Soda  .  20-7        "        5-3      "                        " 

Lime  .  12  3        «        3-45    *'                       « 

Magnesia  4-35      "        169    ''  " 


51-45  12  84 

And  if  the  quantity  of  oxygen  of  the  bases  in  com- 
bination with  sulphuric  and  phosphoric  acid,  viz. 
1-37,  be  again  subtracted  from  12*84,  11*47  parts 
remain  as  the  amount  of  oxygen  contained  in  the 
bases  which  were  in  combination  with  organic  acids. 
These  remarkable  approximations  cannot  be  acci- 
dental ;  and  if  further  examinations  confirm  them 
in  other  kinds  of  plants,  no  other  explanation  than 
that  already  given  can  be  adopted. 

*  This  calculation  is  exact  only  in  the  case  where  the  quantity  of 
ashes  is  equal  in  weight  for  a  given  quantity  of  wood  ;  the  difference 
cannot,  however,  be  admitted  to  be  so  great  as  to  change  sensibly  the 
above  proportions.  Berthier  has  not  mentioned  the  proportion  of  ashes 
contained  in  the  wood. 


112  OF  THE   INORGANIC  CONSTITUENTS  OF  PLANTS. 

It  is  not  known  in  what  form  silica,  manganese, 
and  oxide  of  iron,  are  contained  in  plants  ;  but  we 
are  certain  that  potash,  soda,  and  magnesia,  can  be 
extracted  from  all  parts  of  their  structure  in  the 
form  of  salts  of  organic  acids.  The  same  is  the 
case  with  lime,  when  not  present  as  insoluble  oxalate 
of  lime.  It  must  here  be  remembered,  that  in  plants 
yielding  oxalic  acid,  the  acid  and  potash  never  exist 
in  the  form  of  a  neutral  or  quadruple  salt,  but  always 
as  a  double  acid  salt,  on  whatever  soil  they  may 
grow.  The  potash  in  grapes  also,  is  more  frequently 
found  as  an  acid  salt,  viz.  cream  of  tartar  (bitartrate 
of  potash),  than  in  the  form  of  a  neutral  compound. 
As  these  acids  and  bases  are  never  absent  from 
plants,  and  as  even  the  form  in  which  they  present 
themselves  is  not  subject  to  change,  it  may  be 
affirmed  that  they  exercise  an  important  influence 
on  the  development  of  the  fruits  and  seeds,  and  also 
on  many  other  functions  of  the  nature  of  which  we 
are  at  present  ignorant. 

The  quantity  of  alkaline  bases  existing  in  a  plant 
also  depends  evidently  on  this  circumstance  of  their 
existing  only  in  the  form  of  acid  salts,  —  for  the 
capacity  of  saturation  of  an  acid  is  constant;  and 
when  w^e  see  oxalate  of  lime  in  the  lichens  occupy- 
ing the  place  of  woody  fibre  which  is  absent,  we 
must  regard  it  as  certain  that  the  soluble  organic 
salts  are  destined  to  fulfil  equally  important  though 
different  functions,  so  much  so  that  we  could  not 
conceive  the  complete  development  of  a  plant  with- 
out their  presence,  that  is,  without  the  presence  of 
their  acids,  and  consequently  of  their  bases. 

From  these  considerations  we  must  perceive,  that 
exact  and  trustworthy  examinations  of  the  ashes  of 
plants  of  the  same  kind  growing  upon  different  soils 
would  be  of  the  greatest  importance  to  vegetable 
physiology,  and  would  decide  whether  the  facts 
above  mentioned  are  the  results  of  an  unchanging 
law  for  each  family  of  plants,  and  whether  an  inva- 
riable  number  can  be  found  to  express  the  quantity 


SUBSTITUTION  OF  ALKALINE  BASES.  113 

of  oxygen  which  each  species  of  plant  contains  in 
the  bases  united  with  organic  acids.  In  all  proba- 
bility such  inquiries  will  lead  to  most  important 
results ;  for  it  is  clear  that  if  the  production  of  a 
certain  unchanging  quantity  of  an  organic  acid  is 
required  by  the  peculiar  nature  of  the  organs  of  a 
plant,  and  is  necessary  to  its  existence,  then  potash 
or  lime  must  be  taken  up  by  it  in  order  to  form  salts 
with  this  acid;  that  if  these  do  not  exist  in  suffi- 
cient quantity  in  the  soil,  other  bases  must  supply 
their  place ;  and  that  the  progress  of  a  plant  must 
be  wholly  arrested  when  none  are  present. 

Seeds  of  the  Salsola  Kali,  when  sown  in  common 
garden  soil,  produce  a  plant  containing  both  potash 
and  soda ;  while  the  plants  grown  from  the  seeds  of 
this  contain  only  salts  of  potash,  with  mere  traces 
of  muriate  of  soda.     (Cadet.) 

The  examples  cited  above,  in  which  the  quantity 
of  oxygen  contained  in  the  bases  was  shown  to  be 
the  same,  lead  us  to  the  legitimate  conclusion,  that 
the  development  of  certain  plants  is  not  retarded 
by  the  substitution  of  the  bases  contained  in  them. 
But  it  was  by  no  means  inferred  that  any  one  base 
could  replace  all  the  others,  which  are  found  in  a 
plant  in  its  normal  condition.  On  the  contrary,  it 
is  known  that  certain  bases  are  indispensable  for  the 
growth  of  a  plant,  and  these  could  not  be  substituted 
without  injuring  its  development.  Our  inference  has 
been  drawn  from  certain  plants,  which  can  bear 
without  injury  this  substitution ;  and  it  can  only  be 
extended  to  those  plants  which  are  in  the  same  con- 
dition. It  will  be  shown  afterwards  that  corn  or 
vines  can  only  thrive  on  soils  containing  potash,  and 
that  this  alkali  is  perfectly  indispensable  to  their 
growth.  Experiments  have  not  been  sufficiently 
multiplied  so  as  to  enable  us  to  point  out  in  what 
plants  potash  or  soda  may  be  replaced  by  lime  or 
magnesia ;  we  are  only  warranted  in  affirming  that 
such  substitutions  are  in  many  cases  common.  The 
ashes  of  various  kinds  of  plants  contain  very  differ- 

10* 


114  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

ent  quantities  of  alkaline  bases,  such  as  potash,  soda, 
lime,  or  magnesia.  When  lime  exists  in  the  ashes 
in  large  proportion,  the  quantity  of  magnesia  is  di- 
minished, and  in  like  manner  according  as  the  latter 
increases  the  lime  or  potash  decreases.  In  many  kinds 
of  ashes  not  a  trace  of  magnesia  can  be  detected. 

The  existence  of  vegetable  alkalies  in  combination 
with  organic  acids  gives  great  weight  to  the  opinion, 
that  alkaline  bases  in  general  are  connected  with 
the  development  of  plants. 

If  potatoes  are  grown  where  they  are  not  supplied 
with  earth,  the  magazine  of  inorganic  bases,  (in 
cellars,  for  example,)  a  true  alkali,  called  Solanin, 
of  very  poisonous  nature,  is  formed  in  the  sprouts 
which  extend  towards  the  light,  while  not  the  small- 
est trace  of  such  a  substance  can  be  discovered  in 
the  roots,  herbs,  blossoms,  or  fruits  of  potatoes 
grown  in  fields.  (Otto.)*  In  all  the  species  of  the 
Cinchona,  kinic  acid  is  found ;  but  the  quantity  of 
quinia,  cinchonina,  and  lime,  which  they  contain  is 
most  variable.  From  the  fixed  bases  in  the  products 
of  incineration,  however,  we  may  estimate  pretty 
accurately  the  quantity  of  the  peculiar  organic  bases. 
A  maximum  of  the  first  corresponds  to  a  minimum  of 
the  latter,  as  must  necessarily  be  the  case  if  they 
mutually  replace  one  another  according  to  their 
equivalents.  We  know  that  different  kinds  of  opium 
contain  meconic  acid  in  combination  with  very  dif- 
ferent quantities  of  narcotina,  morphia,  codeia,  &c., 
the  quantity  of  one  of  these  alkaloids  diminishing 
on  the  increase  of  the   others.     Thus  the   smallest 


The  analysis  of  potatoes  afforded  M.  Henry 

Starch 13.30 

Water 73.12 

Albumen 0.92 

Uncrystallizable  sugar 3.30 

Volatile  poisonous  matter             •        .        •        .  0,05 

Peculiar  fatty  matter 1.12 

Parenchyma         ....••.  6.79 

Malic  acid  and  salts 1.40 

100.00 


EXCREMENTS  OF  PLANTS.  115 

quantity  of  morphia  is  accompanied  by  a  maximum 
of  narcotina.  Not  a  trace  of  meconic  acid*  can  be 
discovered  in  many  kinds  of  opium,  but  there  is  not 
on  this  account  an  absence  of  acid,  for  the  meconic 
is  here  replaced  by  sulphuric  acid.  Here,  also,  we 
have  an  example  of  what  has  been  before  stated,  for 
in  those  kinds  of  opium  where  both  these  acids  ex- 
ist, they  are  always  found  to  bear  a  certain  relative 
proportion  to  one  another.  Attention  to  these  facts 
must  be  very  important  in  the  selection  of  soils  des- 
tined for  the  cultivation  of  plants  which  yield  the 
vegetable  alkaloids. 

Now  if  it  be  found,  as  appears  to  be  the  case  in 
the  juice  of  poppies,  that  an  organic  acid  may  be  re- 
placed by  an  inorganic,  without  impeding  the  growth 
of  a  plant,  we  must  admit  the  probability  of  this  sub- 
stitution taking  place  in  a  much  higher  degree  in  the 
case  of  the  inorganic  bases. 

When  roots  find  their  more  appropriate  base  in 
sufficient  quantity,  they  will  take  up  less  of  another. 

These  phenomena  do  not  show  themselves  so  fre- 
quently in  cultivated  plants,  because  they  are  sub- 
jected to  special  external  conditions  for  the  purpose 
of  the  production  of  particular  constituents  or  par- 
ticular organs. 

When  the  soil,  in  which  a  white  hyacinth  is  grow- 
ing in  a  state  of  blossom,  is  sprinkled  with  the  juice 
of  the  Phytolacca  decandra^^  the  white  blossoms  as- 
sume in  one  or  two  hours  a  red  color,  which  again 
disappears  after  a  few  days  under  the  influence  of 
sunshine,  and  they  become  white  and  colorless  as 
before.J  The  juice  in  this  case  evidently  enters  into 
all  parts  of  the  plant,  without  being  at  all  changed 
in  its  chemical  nature,  or  without  its  presence  being 
apparently  either   necessary  or  injurious.     But  this 

*  Robiquet  did  not  obtain  a  trace  of  meconate  of  lime  from  300  lbs. 
of  opium,  whilst  in  other  kinds  the  quantity  was  very  considerable. 
Ann.  de  Chim.  liii.  p.  425. 

t  American  nightshade. 

t  Biot,  in  the  Comptcs  rendus  des  Stances  de  VAcadimie  des  Sciences, 
^  Farisy  ler  S6mestre,  1837,  p.  18. 


116  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

condition  is  not  permanent,  and  when  the  blossoms 
have  again  become  colorless,  none  of  the  coloring 
matter  remains  ;  and  if  it  should  occur  that  any  of 
its  elements  were  adapted  for  the  purposes  of  nutri- 
tion of  the  plant,  then  these  alone  would  be  retained, 
whilst  the  rest  would  be  excreted  in  an  altered  form 
by  the  roots. 

Exactly  the  same  thing  must  happen  when  we 
sprinkle  a  plant  with  a  solution  of  chloride  of  potas- 
sium, nitre,  or  nitrate  of  strontia ;  they  will  enter 
into  the  different  parts  of  the  plant,  just  as  the  col- 
ored juice  mentioned  above,  and  will  be  found  in 
its  ashes  if  it  should  be  burnt  at  this  period.  Their 
presence  is  merely  accidental ;  but  no  conclusion  can 
be  hence  deduced  against  the  necessity  of  the  pres- 
ence of  other  bases  in  plants.  The  experiments  of 
Macaire-Princep  have  shown,  that  plants  made  to 
vegetate  with  their  roots  in  a  weak  solution  of  ace- 
tate of  lead,  and  then  in  rain-water,  yield  to  the  lat- 
ter all  the  salt  of  lead  which  they  had  previously  ab- 
sorbed. They  return,  therefore,  to  the  soil  all  mat- 
ters which  are  unnecessary  to  their  existence.  Again, 
when  a  plant,  freely  exposed  to  the  atmosphere,  rain, 
and  sunshine,  is  sprinkled  with  a  solution  of  nitrate 
of  strontia,  the  salt  is  absorbed,  but  it  is  again  sep- 
arated by  the  roots  and  removed  further  from  them 
by  every  shower  of  rain,  which  moistens  the  soil,  so 
that  at  last  not  a  trace  of  it  is  to  be  found  in  the 
plant. 

Let  us  consider  the  composition  of  the  ashes  of 
two  fir-trees  as  analyzed  by  an  acute  and  most  accu- 
rate chemist.  One  of  these  grew  in  Norway,  on  a 
soil  the  constituents  of  which  never  changed,  but  to 
which  soluble  salts,  and  particularly  common  salt, 
were  conveyed  in  great  quantity  by  rain-water.  How 
did  it  happen  that  its  ashes  contained  no  appreciable 
trace  of  salt,  although  we  are  certain  that  its  roots 
must  have  absorbed  it  after  every  shower  ? 

We  can  explain  the  absence  of  salt  in  this  case  by 
means  of  the  direct  and  positive  observations  refer- 


EXCREMENTS  OF  PLANTS.  117 

red  to,  which  have  shown  that  plants  have  the  power 
of  returning  to  the  soil  all  substances  unnecessary 
to  their  existence ;  and  the  conclusion  to  which  all 
the  foregoing  facts  lead  us,  when  their  real  value  and 
bearing  are  apprehended,  is  that  the  alkaline  bases 
existing  in  the  ashes  of  plants  must  be  necessary  to 
their  growth,  since  if  this  were  not  the  case  they 
would  not  be  retained. 

The  perfect  development  of  a  plant,  according  to 
this  view,  is  dependent  on  the  presence  of  alkalies 
or  alkaline  earths ;  for  when  these  substances  are 
totally  wanting  its  growth  will  be  arrested,  and  when 
they  are  only  deficient  it  must  be  impeded. 

In  order  to  apply  these  remarks,  let  us  compare 
two  kinds  of  trees,  the  wood  of  which  contains  une- 
qual quantities  of  alkaline  bases,  and  we  shall  find 
that  one  of  these  grows  luxuriantly  in  several  soils 
upon  which  the  others  are  scarcely  able  to  vegetate. 
For  example,  10,000  parts  of  oak-wood  yield  250 
parts  of  ashes,  the  same  quantity  of  fir-wood  only 
83,  of  linden-wood  500,  of  rye  440,  and  of  the  herb 
of  the  potato-plant  1500  parts.* 

Firs  and  pines  find  a  sufficient  quantity  of  alkalies 
in  granitic  and  barren  sandy  soils  in  which  oaks  will 
not  grow ;  and  wheat  thrives  in  soils  favorable  for 
the  linden-tree,  because  the  bases  which  are  neces- 
sary to  bring  it  to  complete  maturity,  exist  there  in 
sufficient  quantity.  The  accuracy  of  these  conclu- 
sions, so  highly  important  to  agriculture  and  to  the 
cultivation  of  forests,  can  be  proved  by  the  most 
evident  facts. 

All  kinds  of  grasses,  the  Eqiiisetacece^  for  exam- 
ple, contain  in  the  outer  parts  of  their  leaves  and 
stalk  a  large  quantity  of  silicic  acid  and  potash  in 
the  form  of  acid  silicate  of  potash.  The  proportion 
of  this  salt  does  not  vary  perceptibly  in  the  soil  of 
corn-fields,  because  it  is  again  conveyed  to  them  as 
manure  in  the  form  of  putrefying  straw.     But  this  is 


•  Berthier,  Jinnales  de  Chimie  et  de  Physique,  t.  xxx.  p.  248. 


118  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

not  the  case  in  a  meadow,  and  hence  we  never  find  a 
luxuriant  crop  of  grass  *  on  sandy  and  calcareous 
soils,  which  contain  little  potash,  evidently  because 
one  of  the  constituents  indispensable  to  the  growth 
of  the  plants  is  wanting.  Soils  formed  from  basalt, 
grauwacke,  and  porphyry,  are,  ccBteris  paribus,  the 
best  for  meadow-land,  on  account  of  the  quantity  of 
potash  which  enters  into  their  composition.  The 
potash  abstracted  by  the  plants  is  restored  during 
the  annual  irrigation.  The  potash  contained  in  the 
soil  itself  is  inexhaustible  in  comparison  with  the 
quantity  removed  by  plants.  But  when  we  increase 
the  crop  of  grass  in  a  meadow  by  means  of  gypsum, 
we  remove  a  greater  quantity  of  potash  with  the  hay 
than  can  under  the  same  circumstances  be  restored. 
Hence  it  happens  that,  after  the  lapse  of  several 
years,  the  crops  of  grass  on  the  meadows  manured 
with  gypsum  diminish,  owing  to  the  deficiency  of 
potash.  But  if  the  meadow  be  strewed  from  time  to 
time  with  wood-ashes,  even  with  the  lixiviated  ashes 
which  have  been  used  by  soap-boilers,  (in  Germany 
much  soap  is  made  from  the  ashes  of  wood,)  then 
the  grass  thrives  as  luxuriantly  as  before.  The  ash- 
es are  only  a  means  of  restoring  the  potash,  f 

*  It  would  be  of  importance  to  examine  what  alkalies  are  contained 
in  the  ashes  of  the  seashore  plants  which  grow  in  the  humid  hollows 
of  downs,  and  especially  in  those  of  the  millet-grass.  If  potash  is  not 
found  in  them,  it  must  certainly  be  replaced  by  soda  as  in  the  Salsola^ 
or  by  lime  as  in  the  Plumbaginece.  —  L. 

t  The  compost  which  has  been  employed  with  most  advantage  as  a 
top  dressing  to  grass  by  Mr.  Haggerston,  on  the  estate  of  J.  P.  Gushing, 
Esq.,  at  Watertown,  is  prepared  from  peat  and  barilla  alone. 

The  peat  previously  cut  and  dried  is  made  into  heaps  with  alternate 
layers  of  barilla,  the  thickness  of  each  layer  of  peat  being  eight  inches, 
and  of  the  barilla  four  inches.  This  heap  is  allowed  to  remain  undis- 
turbed during  the  winter,  in  the  spring  it  is  carefully  turned  and  then 
allowed  to  remain  until  the  ensuing  autumn,  when  it  is  spread  upon 
the  land. 

Peat  which  is  to  be  ploughed  into  the  land,  having  been  deposited  in 
the  yard  to  which  swine  have  free  access,  is  mixed  with  stable  manure 
in  the  proportion  of  two  thirds  peat  to  one  third  manure. 

Barilla  is  the  crude  soda  which  is  imported  from  Spain,  Sicily,  &c., 
where  it  is  prepared  by  burning  the  plant  called  salsola  soda.  Accord- 
ing to  Dr.  Ure  it  contains  20  per  cent,  of  real  alkali  (soda)  with  muri- 
ates and  sulphates  of  soda,  some  lime  and  alumina,  with  yery  little 
sulphur. 


REPLACEMENT  OF  EXHAUSTED  ALKALIES.  119 

A  harvest  of  grain  is  obtained  every  thirty  or  forty 
years  from  the  soil  of  the  Luneburg  heath,  by  strew- 
ing it  with  the  ashes  of  the  heath-plants  (^Erica  vul- 
garis) which  grow  on  it.  These  plants  during  the 
long  period  just  mentioned  collect  the  potash  and 
s-oda,  which  are  conveyed  to  them  by  rain-water ; 
and  it  is  by  means  of  these  alkalies  that  oats,  barley, 
and  rye,  to  which  they  are  indispensable,  are  ena- 
bled to  grow  on  this  sandy  heath. 

The  woodcutters  in  the  vicinity  of  Heidelberg  have 
the  privilege  of  cultivating  the  soil  for  their  own  use, 
after  felling  the  trees  used  for  making  tan.  Before 
sowing  the  land  thus  obtained,  the  branches,  roots, 
and  leaves,  are  in  every  case  burned,  and  the  ashes 
used  as  a  manure,  which  is  found  to  be  quite  indis- 
pensable for  the  growth  of  the  grain.  The  soil  itself 
upon  which  the  oats  grow  in  this  district  consists  of 
sandstone ;  and  although  the  trees  find  in  it  a  quan- 
tity of  alkaline  earths  sufficient  for  their  own  suste- 
nance, yet  in  its  ordinary  condition  it  is  incapable 
of  producing  grain. 

The  most  decisive  proof  of  the  use  of  strong 
manure  was  obtained  at  Bingen  (a  town  on  the 
Rhine),  where  the  produce  and  development  of  vines 
were  highly  increased  by  manuring  them  with  such 
substances  as  shavings  of  horn,  &c. ;  but  after  some 
years  the  formation  of  the  wood  and  leaves  de- 
creased to  the  great  loss  of  the  possessor,  to  such 
a  degree  that  he  has  long  had  cause  to  regret  his 
departure  from  the  usual  methods.  By  the  manure 
employed  by  him,  the  vines  had  been  too  much 
hastened  in  their  growth;  in  two  or  three  years 
they  had  exhausted  the  potash  in  the  formation  of 
their  fruit,  leaves,  and  wood,  so  that  none  remained 
for  the  future  crops,  his  manure  not  having  con- 
tained any  potash. 

There  are  vineyards  on  the  Rhine  the  plants  of 
which  are  above  a  hundred  years  old,  and  all  of 
these  have  been  cultivated  by  manuring  them  with 
cow-dung,  a  manure  containing  a  large  proportion 


120  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

of  potash,  although  very  little  nitrogen.  All  the 
potash,  in  fact,  which  is  contained  in  the  food  con- 
sumed by  a  cow  is  again  immediately  discharged  in 
its  excrements. 

The  experience  of  a  proprietor  of  land  in  the 
vicinity  of  Gottingen  offers  a  most  remarkable  ex- 
ample of  the  incapability  of  a  soil  to  produce  wheat 
or  grasses  in  general,  when  it  fails  in  any  one  of 
the  materials  necessary  to  their  growth.  Jn  order 
to  obtain  potash,  he  planted  his  whole  land  with 
wormwood,  the  ashes  of  which  are  well  known  to 
contain  a  large  proportion  of  the  carbonate  of  that 
alkali.  The  consequence  was,  that  he  rendered  his 
land  quite  incapable  of  bearing  grain  for  many  years, 
in  consequence  of  having  entirely  deprived  the  soil 
of  its  potash. 

The  leaves  and  small  branches  of  trees  contain 
the  most  potash ;  and  the  quantity  of  them  which  is 
annually  taken  from  a  wood,  for  the  purpose  of 
being  employed  as  litter,*  contains  more  of  that  alkali 
than  all  the  old  wood  which  is  cut  down.  The  bark 
and  foliage  of  oaks,  for  example,  contain  from  6  to 
9  per  cent,  of  this  alkali;  the  needles  of  firs  and 
pines,  8  per  cent. 

With  every  2920  lbs.  of  firwood  which  are  yearly 
removed  from  an  acre  of  forest,  only  from  0*125  to 
0*58  lbs.  of  alkalies  are  abstracted  from  the  soil, 
calculating  the  ashes  at  0*83  per  cent.  The  moss, 
however,  which  covers  the  ground,  and  of  which  the 
ashes  are  known  to  contain  so  much  alkali,  con- 
tinues uninterrupted  in  its  growth,  and  retains  that 
potash  on  the  surface,  which  would  otherwise  so 
easily  penetrate  with  the  rain  through  the  sandy 
soil.    By  its  decay,  an  abundant  provision  of  alkalies 

*  This  refers  to  a  custom  some  time  since  very  prevalent  in  Ger- 
many, although  now  discontinued.  The  leaves  and  small  twigs  of 
trees  were  gleaned  from  the  forests  by  poor  people,  for  the  purpose 
of  being  used  as  litter  for  their  cattle.  The  trees,  however,  were 
found  to  suffer  so  much  in  consequence,  that  their  removal  is  now 
strictly  prohibited.  The  cause  of  the  injury  was  that  stated  in  the 
text.  — Ed.] 


NECESSITY  OF  CERTAIN  CONDITIONS  FOR  NUTRITION.       121 

is  supplied  to  the  roots  of  the  trees,  and  a  fresh 
supply  is  rendered  unnecessary. 

The  supposition  of  alkalies,  metallic  oxides,  or  in- 
organic matter  in  general,  being  produced  by  plants, 
is  entirely  refuted  by  these  well-authenticated  facts. 

It  is  thought  very  remarkable,  that  those  plants 
of  the  grass  tribe,  the  seeds  of  which  furnish  food 
for  man,  follow  him  like  the  domestic  animals.  But 
saline  plants  seek  the  seashore  or  saline  springs, 
and  the  Chenopodiupi  the  dunghill  from  similar 
causes.  Saline  plants  require  common  salt,  and  the 
plants  which  grow  only  on  dunghills  need  ammonia 
and  nitrates,  and  they  are  attracted  whither  these 
can  be  found,  just  as  the  dung-fly  is  to  animal  ex- 
crements. So  likewise  none  of  our  corn-plants  can 
bear  perfect  seeds,  that  is,  seeds  yielding  flour, 
without  a  large  supply  of  phosphate  of  magnesia  and 
ammonia,  substances  which  they  require  for  their 
maturity.  And  hence,  these  plants  grow  only  in  a 
soil  where  these  three  constituents  are  found  com- 
bined, and  no  soil  is  richer  in  them  than  those 
where  men  and  animals  dwell  together ;  where  the 
urine  and  excrements  of  these  are  found  corn-plants 
appear,  because  their  seeds  cannot  attain  maturity  un- 
less supplied  with  the  constituents  of  those  matters. 

When  we  find  sea-plants  near  our  salt-works, 
several  hundred  miles  distant  from  the  sea,  we  know 
that  their  seeds  have  been  carried  there  in  a  very 
natural  manner,  namely,  by  wind  or  birds,  which 
have  spread  them  over  the  whole  surface  of  the 
earth,  although  they  grow  only  in  those  places  in 
which  they  find  the  conditions  essential  to  their  life. 

Numerous  small  fish,  of  not  more  than  two  inches 
in  length  (  Gasterosteus  aculeatus),  are  found  in  the 
salt-pans  of  the  graduating  house  at  Nidda  (a  vil- 
lage in  Hesse  Darmstadt).  No  living  animal  is  found 
in  the  salt-pans  of  Neuheim,  situated  about  18  miles 
from  Nidda ;  but  the  water  there  contains  so  much 
carbonic  acid  and  lime,  that  the  walls  of  the  gradu- 
ating house  are  covered  with  stalactites.  Hence 
11 


122  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

the  eggs  conveyed  to  this  place  by  birds  do  not 
find  the  conditions  necessary  for  their  development, 
which  they  found  in  the  former  place.* 

How  much  more  wonderful  and  inexplicable  does 
it  appear,  that  bodies  which  remain  fixed  in  the 
strong  heat  of  a  fire,  have  under  certain  conditions 
the  property  of  volatilizing,and,  at  ordinary  tempera- 
tures, of  passing  into  a  state,  of  which  we  cannot 
say  whether  they  have  really  assumed  the  form  of  a 
gas  or  are  dissolved  in  one ;  Steam  or  vapors  in 
general  have  a  very  singular  influence  in  causing 
the  volatilization  of  such  bodies,  that  is,  of  causing 
them  to  assume  the  gaseous  form.  A  liquid  during 
evaporation  communicates  the  power  of  assuming 
the  same  state  in  a  greater  or  less  degree  to  all  sub- 
stances dissolved  in  it,  although  they  do  not  of 
themselves  possess  that  property. 

Boracic  acidf  is  a  substance  which  is  completely 
fixed  in  the  fire ;  it  suffers  no  change  of  weight  ap- 
preciable by  the  most  delicate  balance,  when  ex- 
posed to  a  white  heat,  and,  therefore,  it  is  not 
volatile.  Yet  its  solution  in  water  cannot  be  evap- 
orated by  the  gentlest  heat,  without  the  escape  of  a 
sensible  quantity  of  the  acid  with  the  steam.  Hence 
it  is  that  a  loss  is  always  experienced  in  the  analysis 
of  minerals   containing    this   acid,  when  liquids   in 

*  The  itch-insect  (Acarus  Scahiei)  is  considered  by  Burdach  as  the 
production  of  a  morbid  condition,  so  likewise  lice  in  children ;  the 
original  generation  of  the  fresh- water  muscle  (mytilus)  in  fish-ponds, 
of  sea- plants  in  the  vicinity  of  salt-works,  of  nettles  and  grasses,  of 
fish  in  pools  of  rain,  of  trout  in  mountain  streams,  &c.,  is  according  to 
the  same  natural  philosopher  not  impossible.  A  soil  consisting  of 
crumbled  rocks,  decayed  vegetables,  rain  and  salt  water,  &c.,  is  here 
supposed  to  possess  the  power  of  generating  shellfish,  trout,  and  salt- 
wort (salicornia).  All  inquiry  is  arrested  by  such  opinions,  when 
propagated  by  a  teacher  who  enjoys  a  merited  reputation,  obtained  by 
knowledge  and  hard  labor.  These  subjects,  however,  have  hitherto 
met  with  the  most  superficial  observation,  although  they  well  merit 
strict  investigation.  The  dark,  the  secret,  the  mysterious,  the  enigmatic, 
is,  in  fact,  too  seducing  for  the  youthful  and  philosophic  mind,  which 
would  penetrate  the  deepest  depths  of  nature,  without  the  assistance 
of  the  shaft  or  ladder  of  the  miner.  This  is  poetry,  but  not  sober 
philosophical  inquiry. 

f  The  acid  from  borax. 


INORGANIC  ORIGIN  OF  AMMONIA.  123 

which  it  is  dissolved  are  evaporated.  The  quantity 
of  boracic  acid  which  escapes  with  a  cubic  foot  of 
steam,  at  the  temperature  of  boiling  water,  cannot 
be  detected  by  our  most  sensible  re-agents;  and 
nevertheless  the  many  hundred  tons  annually  brought 
from  Italy  as  an  article  of  commerce,  are  procured 
by  the  uninterrupted  accumulation  of  this  apparently 
inappreciable  quantity.  The  hot  steam  which  issues 
from  the  interior  of  the  earth  is  allowed  to  pass 
through  cold  water  in  the  lagoons  of  Castel  Nuova 
and  Cherchiago ;  in  this  way  the  boracic  acid  is 
gradually  accumulated,  till  at  last  it  may  be  ob- 
tained in  crystals  by  the  evaporation  of  the  water. 
It  is  evident,  from  the  temperature  of  the  steam,  that 
it  must  have  come  out  of  depths  in  which  human 
beings  and  animals  never  could  have  lived,  and  yet 
it  is  very  remarkable  and  highly  important  that  am- 
monia is  never  absent  from  it.  In  the  large  works 
in  Liverpool,  where  natural  boracic  acid  is  con- 
verted into  borax,  many  hundred  pounds  of  sulphate 
of  ammonia  are  obtained  at  the  same  time. 

This  ammonia  has  not  been  produced  hy  the  ani- 
mal organism,  it  existed  before  the  creation  of  human 
beings ;  it  is  a  part,  a  primary  constituent,  of  the 
globe  itself* 

The  experiments  instituted  under  Lavoisier's  guid- 
ance by  the  Direction  des  Poudres  et  Saltpetres,  have 
proved  that  during  the  evaporation  of  the  saltpetre 
ley,  the  salt  volatilizes  with  the  water,  and  causes 
a  loss  which  could  not  before  be  explained.  It  is 
known  also,  that  in  sea-storms,  leaves  of  plants  in 
the  direction  of  the  wind  are  covered  with  crystals 
of  salt,  even  at  the  distance  of  from  20  to  30  miles 
from  the  sea.f  But  it  does  not  require  a  storm  to 
cause  the  volatilization  of  the  salt,  for  the  air  hang- 
ing over  the  sea  always  contains  enough  of  this  sub- 
stance to  make  a  solution  of  nitrate  of  silver  turbid, 

*  See  extract  from  Professor  Daubeny's  Lectures^  in  Appendix, 
t  Tiiis  was  observed  in  the  United  States  after  the  great  storm  of 
September  23,  1815.    See  Professor  Farrar's  account  in  Mem.  A.  A.  S. 


124  OF  THE  INORGANIC  CONSTITUENTS  OF  PLANTS. 

and  every  breeze  must  carry  this  away.  Now,  as 
thousands  of  tons  of  sea-water  annually  evaporate 
into  the  atmosphere,  a  corresponding  quantity  of  the 
salts  dissolved  in  it,  viz.  of  common  salt,  chloride 
of  potassium,  magnesia,  and  the  remaining  constitu- 
ents of  the  sea-water,  will  be  conveyed  by  wind  to 
the  land. 

This  volatilization  is  a  source  of  considerable  loss 
in  salt-works,  especially  where  the  proportion  of 
salt  in  the  water  is  not  large.  This  has  been  com- 
pletely proved  at  the  salt-works  of  Nauheim,  by  the 
very  intelligent  director  of  that  establishment,  M. 
Wilhelmi.  He  hung  a  plate  of  glass  between  two 
evaporating  houses,  which  were  about  1200  paces 
distant  from  each  other,  and  found  in  the  morning, 
after  the  drying  of  the  dew,  that  the  glass  was 
covered  with  crystals  of  salt  on  one  or  the  other 
side,  according  to  the  direction  of  the  wind. 

By  the  continual  evaporation  of  the  sea,  its  salts  * 
are  spread  over  the  whole  surface  of  the  earth ;  and 
being  subsequently  carried  down  by  the  rain,  furnish 

*  Analyses  of  sea- water. 

Of  the  British  Channel.       Of  the  Mediterranean. 

—  Schweitzer.  — Laurens. 
In  1000  parts.  —  Marcet.              Grs.  Grs. 

Water  964.74372  959.26 

Chloride  of  Sodium  26.660  27.05948  27.22 

"       of  Potassium        1.232  0.76552  0.01 

"       of  Magnesium     5.152  3.66658  6.14 

Bromide  of        Do.        0.02929  

Sulphate  of  Soda  4.660  

»       of  Lime  1.5  1.40662  0.15 

"       of  Magnesia        .....  2.29578  7.02 

Carbonate  of  Lime  0.03301  f  ^^^^'  ^'"^^  ^"^  I  0.20 

^      magnesia.       ) 

According  to  M*Clemm,  the  water  of  the  North  Sea  contains  in  1000 

parts, 

24.84  Chloride  of  Sodium. 

2.42  Chloride  of  Magnesium. 

2.06  Sulphate  of  Magnesia. 

1.35  Chloride  of  Potassium. 

1.20  Sulphate  of  Lime. 
In  addition  to  these  constituents,  it  also  contains  inappreciable  quan- 
tities of  carbonate  of  lime,  magnesia,  iron,  manganese,  phosphate  of 
lime,  iodides  and  bromides,  silica,  sulphuretted  hydrogen,  and  organic 
matter,  together  with  ammonia  and  carbonic  acid.  (Liebig's  Annalen 
der  Chemie,  Bd.  xxxvii.  s.  3.) 


CARBONIC  ACID  CONTAINED  IN  SEA-WATER.  125 

to  the  vegetation  those  salts  nacessary  to  its  ex- 
istence. This  is  the  origin  of  the  salts  found  in  the 
ashes  of  plants,  in  those  cases  where  the  soil  could 
not  have  yielded  them. 

In  a  comprehensive  view  of  the  phenomena  of 
nature,  we  have  no  scale  for  that  which  we  are 
accustomed  to  name,  small  or  great ;  all  our  ideas 
are  proportioned  to  what  we  see  around  us,  but  how 
insignificant  are  they  in  comparison  with  the  whole 
mass  of  the  globe  !  that  which  is  scarcely  observable 
in  a  confined  district  appears  inconceivably  large 
when  regarded  in  its  extension  through  unlimited 
space.  The  atmosphere  contains  only  a  thousandth 
part  of  its  weight  of  carbonic  acid ;  and  yet  small 
as  this  proportion  appears,  it  is  quite  sufficient  to 
supply  the  whole  of  the  present  generation  of  living 
beings  with  carbon  for  a  thousand  years,  even  if  it 
were  not  renewed.  Sea-water  contains  j^  of  its 
weight  of  carbonate  of  lime;  and  this  quantity, 
although  scarcely  appreciable  in  a  pound,  is  the 
source  from  which  myriads  of  marine  mollusca  and 
corals  are  supplied  wdth  materials  for  their  habita- 
tions. 

Whilst  the  air  contains  only  from  4  to  6  ten-thou- 
sandth parts  of  its  volume  of  carbonic  acid,  sea- 
water  contains  100  times  more,  (10,000  volumes  of 
sea-w^ater  contain  620  volumes  of  carbonic  acid  — 
Laurent,  Bouillon,  Lagrange).  Ammonia*  is  also 
found  in  this  water,  so  that  the  same  conditions 
which  sustain  living  beings  on  the  land  are  combined 
in  this  medium,  in  which  a  whole  world  of  other 
plants  and  animals  exists. 

The  roots  of  plants  are  constantly  engaged  in 
collecting  from  the  rain  those  alkalies  which  formed 
part  of  the  sea-water,  and  also  those  of  the  water 
of  springs,  which  penetrates  the  soil.  Without 
alkalies  and  alkaline  bases   most   plants   could  not 

*  When  the  solid  saline  residue  obtained  by  the  evaporation  of  sea- 
water  is  heated  in  a  retort  to  redness,  a  sublimate  of  sal-ammoniac  is 
obtained.  —Marcet. 

11* 


126  THE  ART  OF  CULTURE. 

exist,  and  without^plants  the  alkalies  would  disap- 
pear gradually  from  the  surface  of  the  earth. 

When  it  is  considered,  that  sea-water  contains 
less  than  one-millit)nth  of  its  own  weight  of  iodine,* 
and  that  all  combinations  of  iodine  with  the  metallic 
bases  of  alkalies  are  highly  soluble  in  water,  some 
provision  must  necessarily  be  supposed  to  exist  in 
the  organization  of  sea-weed  and  the  different  kinds 
of  Fuci,  by  which  they  are  enabled  during  their  life 
to  extract  iodine  in  the  form  of  a  soluble  salt  from 
sea-water,  and  to  assimilate  it  in  such  a  manner,  that 
it  is  not  again  restored  to  the  surrounding  medium. 
These  plants  are  collectors  of  iodine,  just  as  land- 
plants  are  of  alkalies ;  and  they  yield  us  this  ele- 
ment, in  quantities  such  as  we  could  not  otherwise 
obtain  from  the  water  without  the  evaporation  of 
whole  seas. 

We  take  it  for  granted,  that  the  sea-plants  require 
metallic  iodides  f  for  their  growth,  and  that  their 
existence  is  dependent  on  the  presence  of  those 
substances.  With  equal  justice,  then,  we  conclude, 
that  the  alkalies  and  alkaline  earths,  always  found 
in  the  ashes  of  land-plants,  are  likewise  necessary 
for  their  development. 


CHAPTER  VII. 

THE  ART  OF   CULTURE. 

The  conditions   necessary  for  the  life  of  all  vege- 
tables have   been   considered  in  the  preceding  part 

*  This  substance  was  discovered  in  1812,  and  is  obtained  from  marine 
plants;  it  is  found  aLso  in  sea- water  and  several  mineral  springs  in 
combination  with  hydrogen,  as  hydriodic  acid.  With  bases  this  acid 
forms  hydriodates.  Iodine  has  not  been  decomposed.  It  is  a  solid, 
and  at  about  350°  F.  passes  into  vapor  of  a  beautiful  violet  color ;  hence 
its  name. 

t  Compounds  of  metals  and  iodine. 


USE  OF  HUMUS.  127 

of  the  work.  Carbonic  acid,  ammonia,  and  water 
yield  elements  for  all  the  organs  of  plants.  Certain 
inorganic  substances  —  salts  and  metallic  oxides  — 
serve  peculiar  functions  in  their  organism,  and  many 
of  them  must  be  viewed  as  essential  constituents  of 
particular  parts. 

The  atmosphere  and  the  soil  offer  the  same  kind 
of  nourishment  to  the  leaves  and  roots.  The  former 
contains  a  comparatively  inexhaustible  supply  of 
carbonic  acid  and  ammonia ;  the  latter,  by  means  of 
its  humus,  generates  constantly  fresh  carbonic  acid, 
whilst,  during  the  winter,  rain  and  snow  introduce 
into  the  soil  a  quantity  of  ammonia,  sufficient  for  the 
development  of  the  leaves  and  blossoms. 

The  complete,  or  it  may  be  said,  the  absolute 
insolubility  in  cold  water  of  vegetable  matter  in 
progress  of  decay,  (humus,)  appears  on  closer  con- 
sideration to  be  a  most  wise  arrangement  of  nature. 
For  if  humus  possessed  even  a  smaller  degree  of 
solubility  than  that  ascribed  to  the  substance  called 
humic  acid,  it  must  be  dissolved  by  rain-water. 
Thus,  the  yearly  irrigation  of  meadows,  which  lasts 
for  several  weeks,  would  remove  a  great  part  of  it 
from  the  ground,  and  a  heavy  and  continued  rain 
would  impoverish  a  soil.  But  it  is  soluble  only  when 
combined  with  oxygen ;  it  can  be  taken  up  by  water, 
therefore,  only  as  carbonic  acid. 

When  kept  in  a  dry  place,  humus  may  be  preserved 
for  centuries  ;  but  when  moistened  with  water,  it 
converts  the  surrounding  oxygen  into  carbonic  acid. 
As  soon  as  the  action  of  the  air  ceases,  that  is,  as 
soon  as  it  is  deprived  of  oxygen,  the  humus  suffers 
no  further  change.  Its  decay  proceeds  only  when 
plants  grow  in  the  soil  containing  it;  for  they  ab- 
sorb by  their  roots  the  carbonic  acid  as  it  is  formed. 
The  soil  receives  again  from  living  plants  the  car- 
bonaceous matter  it  thus  loses,  so  that  the  proportion 
of  humus  in  it  does  not  decrease. 

The  stalactitic  caverns  in  Franconia,  and  those  in 
the  vicinity  of  Baireuth,  and  Streitberg,  lie  beneath 


128  THE  ART  OF  CULTURE. 

a  fertile  arable  soil ;  the  abundant  decaying  vege- 
tables or  humus  in  this  soil,  being  acted  on  by 
moisture  and  air,  constantly  evolve  carbonic  acid, 
which  is  dissolved  by  the  rain.  The  rain-water  thus 
impregnated  permeates  the  porous  limestone,  which 
forms  the  walls  and  roofs  of  the  caverns,  and  dis- 
solves in  its  passage  as  much  carbonate  of  lime  as 
corresponds  to  the  quantity  of  carbonic  acid  con- 
tained in  it.  Water  and  the  excess  of  carbonic 
acid  evaporate  from  this  solution  when  it  has  reached 
the  interior  of  the  caverns,  and  the  limestone  is 
deposited  on  the  walls  and  roofs  in  crystalline  crusts 
of  various  forms.  There  are  few  spots  on  the  earth 
where  so  many  circumstances  favorable  to  the  pro- 
duction of  humate  of  lime  are  combined,  if  the 
humus  actually  existed  in  the  soil  in  the  form  of 
humic  acid.  Decaying  vegetable  matter,  water,  and 
lime  in  solution,  are  brought  together,  but  the  sta- 
lactites formed  contain  no  trace  of  vegetable  matter, 
and  no  humic  acid ;  they  are  of  a  glistening  white 
or  yellowish  color,  and  in  part  transparent,  like  cal- 
careous spar,  and  may  be  heated  to  redness  without 
becoming  black. 

The  subterranean  vaults  in  the  old  castles  near 
the  Rhine,  the  "  Bergstrass,"  and  Wetherau,  are 
constructed  of  sandstone,  granite,  or  basalt,  and 
present  appearances  similar  to  the  limestone  caverns. 
The  roofs  of  these  vaults  or  cellars  are  covered 
externally  to  the  thickness  of  several  feet  with 
vegetable  mould,  which  has  been  formed  by  the 
decay  of  plants.  The  rain  falling  upon  them  sinks 
through  the  earth,  and  dissolves  the  mortar  by  means 
of  the  carbonic  acid  derived  from  the  mould ;  and 
this  solution  evaporating  in  the  interior  of  the  vaults, 
covers  them  with  small  thin  stalactites,  which  are 
quite  free  from  humic  acid. 

In  such  a  filtering  apparatus,  built  by  the  hand  of 
nature,  we  have  placed  before  us  experiments  which 
have  been  continued  for  a  hundred  or  a  thousand 
years.     Now,  if  water  possessed   the  power  of  dis- 


INSOLUBILITY  OF  HUMUS.  129 

solving  a  hundred-thousandth  part  of  its  own  weight 
of  humic  acid  or  humate  of  lime,  and  humic  acid 
were  present,  we  should  find  the  inner  surface  of  the 
roofs  of  these  vaults  and  caverns  covered  with  these 
substances ;  but  we  cannot  detect  the  smallest  trace 
of  them.  There  could  scarcely  be  found  a  more 
clear  and  convincing  proof  of  the  absence  of  the 
humic  acid  of  chemists  in  common  vegetable  mould. 

The  common  view,  which  has  been  adopted  re- 
specting the  modus  operandi  of  humic  acid,  does 
not  afford  any  explanation  of  the  following  phenom- 
enon: —  A  very  small  quantity  of  humic  acid  dis- 
solved in  water  gives  it  a  yellow  or  brown  color. 
Hence  it  would  be  supposed  that  a  soil  would  be 
more  fruitful  in  proportion  as  it  was  capable  of  giv- 
ing this  color  to  water,  that  is,  of  yielding  it  humic 
acid.  But  it  is  very  remarkable  that  plants  do  not 
thrive  in  such  a  soil,  and  that  all  manure  must  have 
lost  this  property  before  it  can  exercise  a  favorable 
influence  upon  their  vegetation.  Water  from  barren 
peat  soils  and  marshy  meadows,  upon  which  few 
plants  flourish,  contains  much  of  this  humic  acid  ;  but 
all  agriculturists  and  gardeners  agree  that  the  most 
suitable  and  best  manure  for  plants  is  that  which 
has  completely  lost  the  property  of  giving  a  color 
to  water. 

•The  soluble  substance,  which  gives  to  w^ater  a 
brown  color,  is  a  product  of  the  putrefaction  of  all 
animal  and  vegetable  matters ;  its  formation  is  an 
evidence  that  there  is  not  oxygen  sufficient  to  begin, 
or  at  least  to  complete  the  decay.  The  brown 
solutions  containing  this  substance  are  decolorized 
in  the  air  by  absorbing  oxygen,  and  a  black  coaly 
matter  precipitates  —  the  substance  named  "coal  of 
humus."  Now  if  a  soil  were  impregnated  with  this 
matter,  the  effect  on  the  roots  of  plants  w^ould  be 
the  same  as  that  of  entirely  depriving  the  soil  of 
oxygen ;  plants  would  be  as  little  able  to  grow  in 
such  ground  as  they  would  if  hydrated  protoxide 
of  iron    were    mixed   with  the  soil.     Indeed,  some 


130  THE  ART  OF  CULTURE. 

barren  soils  have  been  found  to  owe  their  sterility 
to  this  very  cause.  The  sulphate  of  protoxide  of 
iron  (copperas),  which  forms  a  constituent  of  these 
soils,  possesses  a  powerful  affinity  for  oxygen,  and 
consequently  prevents  the  absorption  of  that  gas  by 
the  roots  of  plants  in  its  vicinity. "*  All  plants  die 
in  soils  and  water  which  contain  no  oxygen;  absence 
of  air  acts  exactly  in  the  same  manner  as  an  excess 
of  carbonic  acid.  Stagnant  water  on  a  marshy  soil 
excludes  air,  but  a  renewal  of  water  has  the  same 
effect  as  a  renewal  of  air,  because  water  contains  it 
in  solution.  If  the  w^ater  is  withdrawn  from  a  marsh, 
free  access  is  given  to  the  air,  and  the  marsh  is 
changed  into  a  fruitful  meadow. 

In  a  soil  to  which  the  air  has  no  access,  or  at  most 
but  very  little,  the  remains  of  animals  and  vegeta- 
bles do  not  decay,  for  they  can  only  do  so  when 
freely  supplied  with  oxygen;  but  they  undergo  putre- 
faction, for  which  air  is  present  in  sufficient  quan- 
tity. Putrefaction  is  known  to  be  a  most  powerful 
deoxidizing  process,  the  influence  of  which  extends 
to  all  surrounding  bodies,  even  to  the  roots  and  the 
plants  themselves.  All  substances  from  which  oxy- 
gen can  be  extracted  yield  it  to  putrefying  bodies ; 
yellow  oxide  of  iron  passes  into  the  state  of  black 
oxide,  sulphate  of  iron  into  sulphuret  of  iron,  &c. 

The  frequent  renewal  of  air  by  ploughing,  and  the 
preparation  of  the  soil,  especially  its  contact  with 
alkaline  metallic  oxides,  the  ashes  of  brown  coal, 
burnt  lime  or  limestone,  change  the  putrefaction  of 
its  organic  constituents  into  a  pure  process  of  oxi- 
dation ;  and  from  the  moment  at  which  all  the  or- 
ganic matter  existing  in  a  soil  enters  into  a  state 
of  oxidation  or  decay,  its  fertility  is  increased.  The 
oxygen  is  no  longer  employed  for  the  conversion  of 

*  The  most  obvious  method  of  removing  this  salt  from  soils  in  which 
it  may  be  contained  is  to  manure  the  land  with  lime.  The  lime  unites 
with  the  sulphuric  acid  and  liberates  the  protoxide  of  iron,  which  ab- 
sorbs oxyg^en  with  much  rapidity,  and  is  converted  into  the  peroxide 
of  iron.  This  conversion  is  accelerated  by  giving  free  access  to  the 
air,  that  is,  by  loosening  the  soil. 


INSOLUBILITY  OF  HUMUS.  131 

the  brown  soluble  matter  into  the  insoluble  coal  of 
humus,  but  serves  for  the  formation  of  carbonic 
acid.  This  change  takes  place  very  slowly,  and  in 
some  instances  the  oxygen  is  completely  excluded 
by  it ;  and  whenever  this  happens,  the  soil  loses  its 
fertility.  Thus,  in  the  vicinity  of  Salzhausen  (a 
village  in  Hesse  Darmstadt,  famed  for  its  mineral 
springs,)  upon  a  meadow  called  Griinschwalheimer, 
unfruitful  spots  are  seen  here  and  there  covered  with 
a  yellow  grass.  If  a  hole  be  bored  from  twenty  to 
twenty-five  feet  deep  in  one  of  these  spots,  carbonic 
acid  is  emitted  from  it  with  such  violence  that  the 
noise  made  by  the  escape  of  the  gas  may  be  dis- 
tinctly heard  at  the  distance  of  several  feet.  Here 
the  carbonic  acid  rising  to  the  surface  displaces 
completely  all  the  air,  and  consequently  all  the  oxy- 
gen, from  the  soil ;  and  without  oxygen  neither  seeds 
nor  roots  can  be  developed;  a  plant  will  not  vege- 
tate in  pure  nitrogen  or  carbonic  acid  gas.* 

Humus  supplies  young  plants  with  nourishment 
by  the  roots,  until  their  leaves  are  matured  sufficient- 
ly to  act  as  exterior  organs  of  nutrition ;  its  quan- 
tity heightens  the  fertility  of  a  soil  by  yielding  more 
nourishment  in  this  first  period  of  growth,  and  con- 
sequently by  increasing  the  number  of  organs  of 
atmospheric  nutrition.  Those  plants  which  receive 
their  first  food  from  the  substance  of  their  seeds, 
such  as  bulbous  plants,  could  completely  dispense 
with  humus ;  its  presence  is  useful  only  in  so  far  as 
it  increases  and  accelerates  their  development,  but  it 
is  not  necessary,  —  indeed,  an  excess  of  it  at  the 
commencement  of  their  growth  is  in  a  certain  mea- 
sure injurious. 

The  amount  of  food  which  young  plants  can  take 
from  the  atmosphere  in  the  form  of  carbonic  acid 
and  ammonia  is  limited;  they  cannot  assimilate  more 
than  the  air  contains.  Now,  if  the  quantity  of  their 
stems,  leaves,  and  branches  has  been  increased  by 

*  See  note  p.  79. 


132  THE  ART  OF  CULTURE. 

the  excess  of  food  yielded  by  the  soil  at  the  com- 
mencement of  their  development,  they  will  require 
for  the  completion  of  their  growth,  and  for  the  for- 
mation of  their  blossoms  and  fruits,  more  nourish- 
ment from  the  air  than  it  can  afford,  and  consequently 
they  will  not  reach  maturity.  In  many  cases  the 
nourishment  afforded  by  the  air  under  these  circum- 
stances suffices  only  to  complete  the  formation  of 
the  leaves,  stems,  and  branches.  The  same  result 
then  ensues  as  when  ornamental  plants  are  trans- 
planted from  the  pots  in  which  they  have  grown  to 
larger  ones,  in  which  their  roots  are  permitted  to 
increase  and  multiply.  All  their  nourishment  is  em- 
ployed for  the  increase  of  their  roots  and  leaves; 
they  spring,  as  it  is  said,  into  an  herb  or  weed,  but 
do  not  blossom.  When,  on  the  contrary,  we  take 
away  part  of  the  branches,  and  of  course  their  leaves 
with  them,  from  dwarf  trees,  since  we  thus  prevent 
the  development  of  new  branches,  an  excess  of 
nutriment  is  artificially  procured  for  the  trees,  and 
is  employed  by  them  in  the  increase  of  the  blossoms 
and   enlargement  of  the   fruit.     It  is   to  effect  this 

o 

purpose  that  vines  are  pruned. 

A  new  and  peculiar  process  of  vegetation  ensues 
in  all  perennial  plants,  such  as  shrubs,  fruit  and 
forest  trees,  after  the  complete  maturity  of  their 
fruit.  The  stem  of  annual  plants  at  this  period  of 
their  growth  becomes  woody,  and  their  leaves  change 
in  color.  The  leaves  of  trees  and  shrubs,  on  the 
contrary,  remain  in  activity  until  the  commencement 
of  the  winter.  The  formation  of  the  layers  of  wood 
progresses,  the  wood  becomes  harder  and  more. solid, 
but  after  August  the  leaves  form  no  more  wood ;  all 
the  carbonic  acid  which  the  plants  now  absorb  is 
employed  for  the  production  of  nutritive  matter  for 
the  following  year :  instead  of  woody  fibre,  starch  is 
formed,  and  is  diffused  through  every  part  of  the 
plant    by  the    autumnal    sap    (seve    d'Aout).*     Ac- 

*  Hartig,  in  Erdmann  und  Schweigger-Seidels  Journal,  V.  217.  1835. 


EXCESS  OF  NUTRIMENT.  133 

cording  to  the  observations  of  M.  Heyer,  the  starch 
thus  deposited  in  the  body  of  the  tree  can  be  recog- 
nised in  its  known  form  by  the  aid  of  a  good  micro- 
scope. The  barks  of  several  aspens  and  pine-trees  * 
contain  so  much  of  this  substance,  that  it  can  be 
extracted  from  them  as  from  potatoes  by  trituration 
with  water.  It  exists  also  in  the  roots  and  other 
parts  of  perennial  plants.  A  very  early  winter,  or 
sudden  change  of  temperature,  prevents  the  forma- 
tion of  this  provision  for  the  following  year ;  the 
wood,  as  in  the  case  of  the  vine-stock,  does  not 
ripen,  and  its  growth  is  in  the  next  year  very 
limited. 

From  the  starch  thus  accumulated,  sugar  and  gum 
are  produced  in  the  succeeding  spring,  while  from 
the  gum  those  constituents  of  the  leaves  and  young 
sprouts  which  contain  no  nitrogen  are  in  their  turn 
formed.  After  potatoes  have  germinated,  the  quantity 
of  starch  in  them  is  found  diminished.  The  juice  of 
the  maple-tree  ceases  to  be  sweet  from  the  loss  of  its 
sugar  when  its  buds,  blossoms,  and  leaves  attain 
their  maturity. 

The  branch  of  a  willow,  which  contains  a  large 
quantity  of  granules  of  starch  in  every  part  of  its 
woody  substance,  puts  forth  both  roots  and  leaves 
in  pure  distilled  rain-water;  but  in  proportion  as  it 

*  It  is  well  known  that  bread  is  made  from  the  bark  of  pines  in 
Sweden  during  famines. 

The  following  directions  are  given  by  Professor  Autenrieth  for  pre- 
paring a  palatable  and  nutritious  bread  from  the  heecU  and  other  woods 
destitute  of  turpentine.  Every  thing  soluble  in  water  is  first  removed 
by  frequent  maceration  and  boiling,  the  wood  is  then  to  be  reduced  to 
a  minute  state  of  division,  not  merely  into  fine  fibres,  but  actual  pow- 
der ;  and  after  being  repeatedly  subjected  to  heat  in  an  oven,  is  ground 
in  the  usual  manner  of  corn.  Wood  thus  prepared,  according  to  the 
author,  acquires  the  smell  and  taste  of  corn  flour.  It  is,  however, 
never  quite  white.  It  agrees  with  corn  flour  in  not  fermenting  with- 
out the  addition  of  leaven,  and  in  this  case  some  leaven  of  corn  flour  is 
found  to  answer  best.  With  this  it  makes  a  perfectly  uniform  and 
spongy  bread ;  and  when  it  is  thoroughly  baked,  and  has  much  crust, 
it  has  a  much  better  taste  of  bread  than  what  in  time  of  scarcity  is  pre- 
pared from  the  bran  and  husks  of  corn.  Wood-flour  also,  boiled  in 
water,  forms  a  thick,  tough,  trembling  jelly,  which  is  very  nutritious.. 
—  Philosophical  Transactions y  1827. 

12 


134  THE  ART  OF  CULTURE. 

grows,  the  starch  disappears,  it  being  evidently  ex- 
hausted for  the  formation  of  the  roots  and  leaves. 
In  the  course  of  these  experiments,  M.  Heyer  made 
the  interesting  observation,  that  such  branches  when 
placed  in  snow-water  (which  contains  ammonia) 
produced  roots  three  or  four  times  longer  than  those 
which  they  formed  in  pure  distilled  water,  and  that 
this  pure  water  remained  clear,  while  the  rain-water 
gradually  acquired  a  yellow  color. 

Upon  the  blossoming  of  the  sugar-cane,  likewise,, 
part  of  the  sugar  disappears;  and  it  has  been  ascer- 
tained, that  the  sugar  does  not  accumulate  in  the 
beet-root  until  after  the  leaves  are  completely  formed. 

Much  attention  has  recently  been  drawn  to  the 
fact  that  the  produce  of  potatoes  may  be  much  in- 
creased by  plucking  off  the  blossoms  from  the  plants 
producing  them,  a  result  quite  consistent  with  theo- 
ry. This  important  observation  has  been  completely 
confirmed  by  M.  Zeller,  the  director  of  the  Agricul- 
tural Society  at  Darmstadt.  In  the  year  1839,  two 
fields  of  the  same  size,  lying  side  by  side  and  ma- 
nured in  the  same  manner,  were  planted  with  pota- 
toes. When  the  plants  had  flowered,  the  blossoms 
were  removed  from  those  in  one  field,  while  those  in 
the  other  field  were  left  untouched.  The  former  pro- 
duced 47  bolls,  the  latter  only  37  bolls. 

These  well-authenticated  observations  remove  ev- 
ery doubt  as  to  the  part  which  sugar,  starch,  and 
gum  play  in  the  development  of  plants  ;  and  it  ceases 
to  be  enigmatical,  why  these  three  substances  exer- 
cise no  influence  on  the  growth  or  process  of  nutri- 
tion of  a  matured  plant,  when  supplied  to  them  as 
food. 

The  accumulation  of  starch  in  plants  during  the 
autumn  has  been  compared,  although  certainly  erro- 
neously, to  the  fattening  of  hibernating  animals  be- 
fore their  winter  sleep ;  but  in  these  animals  every 
vital  function,  except  the  process  of  respiration,  is 
suspended,  and  they  only  require,  like  a  lamp  slowly 
burning,  a  substance  rich  in  carbon  and  hydrogen  to 


EXCESS  OF  NUTRIMENT.  135 

support  the  process  of  combustion  in  the  lungs.  On 
their  awaking  from  their  torpor  in  the  spring,  the  fat 
has  disappeared,  but  has  not  served  as  nourishment. 
It  has  not  caused  the  least  increase  in  any  part  of 
their  body,  neither  has  it  changed  the  quality  of  any 
of  their  organs.  With  nutrition,  properly  so  called, 
the  fat  in  these  animals  has  not  the  least  connexion. 

The  annual  plants  form  and  collect  their  future 
nourishment  in  the  same  way  as  the  perennial ;  they 
store  it  in  their  seeds  in  the  form  of  vegetable  albu- 
men,  starch  and  gum,  which  are  used  by  the  germs 
for  the  formation  of  their  leaves  and  first  radicle 
fibres.  The  proper  nutrition  of  the  plants,  their  in- 
crease in  size,  begins  after  these  organs   are  formed. 

Every  germ  and  every  bud  of  a  perennial  plant  is 
the  engrafted  embryo  of  a  new  individual,  while  the 
nutriment  accumulated  in  the  stem  and  roots,  corre- 
sponds to  the  albumen  of  the  seeds. 

Nutritive  matters  are,  correctly  speaking,  those 
substances  which,  when  presented  from  without,  are 
capable  of  sustaining  the  life  and  all  the  functions 
of  an  organism,  by  furnishing  to  the  different  parts 
of  plants  the  materials  for  the  production  of  their 
peculiar  constituents. 

In  animals,  the  blood  is  the  source  of  the  material 
of  the  muscles  and  nerves  ;  by  one  of  its  component 
parts,  the  blood  supports  the  process  of  respiration, 
by  others,  the  peculiar  vital  functions ;  every  part  of 
the  body  is  supplied  with  nourishment  by  it,  but  its 
own  production  is  a  special  function,  without  which 
w^e  could  not  conceive  life  to  continue.  If  we  destroy 
the  activity  of  the  organs  which  produce  it,  or  if  we 
inject  the  blood  of  one  animal  into  the  veins  of  an- 
other, at  all  events,  if  we  carry  this  beyond  certain 
limits,  death  is  the  consequence. 

If  we  could  introduce  into  a  tree  woody  fibre  in  a 
state  of  solution,  it  would  be  the  same  thing  as  plac- 
ing a  potato  plant  to  vegetate  in  a  paste  of  starch. 
The  office  of  the  leaves  is  to  form  starch,  woody  fibre, 
and  sugar;    consequently,  if  we  convey  these   sub- 


136  THE  ART  OF  CULTURE. 

stances  through  the  roots,  the  vital  functions  of  the 
leaves  must  cease,  and  if  the  process  of  assimilation 
cannot  take  another  form,  the  plant  must  die. 

Other  substances  must  be  present  in  a  plant,  be- 
sides the  starch,  sugar,  and  gum,  if  these  are  to  take 
part  in  the  development  of  the  germ,  leaves,  and  first 
radicle  fibres.  There  is  no  doubt  that  a  grain  of 
wheat  contains  within  itself  the  component  parts  of 
the  germ  and  of  the  radicle  fibres,  and,  we  must  sup- 
pose, exactly  in  the  proportion  necessary  for  their, 
formation.  These  component  parts  are  starch  and 
gluten;  and  it  is  evident  that  neither  of  them  alone, 
but  that  both  simultaneously  assist  in  the  formation 
of  the  root,  for  they  both  suffer  changes  under  the 
action  of  air,  moisture,  and  a  suitable  temperature. 
The  starch  is  converted  into  sugar,  and  the  gluten 
also  assumes  a  new  form,  and  both  acquire  the  capa- 
bility of  being  dissolved  in  water,  and  of  thus  being 
conveyed  to  every  part  of  the  plant.  Both  the  starch 
and  the  gum  are  completely  consumed  in  the  forma- 
tion of  the  first  part  of  the  roots  and  leaves  ;  an  ex- 
cess of  either  could  not  be  used  in  the  formation  of 
leaves,  or  in  any  other  way. 

The  conversion  of  starch  into  sugar  during  the 
germination  of  grain  is  ascribed  to  a  vegetable  princi- 
ple called  diastase,  which  is  generated  during  the  act 
of  commencing  germination.  But  this  mode  of  trans- 
formation can  also  be  effected  by  gluten,  although  it 
requires  a  longer  time.  Seeds,  which  have  germin- 
ated, always  contain  much  more  diastase  than  is 
necessary  for  the  conversion  of  their  starch  into 
sugar,  for  five  parts  by  weight  of  starch  can  be  con- 
verted into  sugar  by  one  part  of  malted  barley. 
This  excess  of  diastase  can  by  no  means  be  regarded 
as  accidental,  for,  like  the  starch,  it  aids  in  the  form- 
ation of  the  first  organs  of  the  young  plant,  and  dis- 
appears with  the  sugar ;  diastase  contains  nitrogen 
and  furnishes  the  elements  of  vegetable  albumen. 

Carbonic  acid,  water,  and  ammonia,  are  the  food 
of  fully-developed  plants  ;  starch,  sugar,  and  gum. 


CONDITIONS  ESSENTIAL  TO  NtJTRITION.  137 

serve,  when  accompanied  by  an  azotized  substance, 
to  sustain  the  embryo,  until  its  first  organs  of  nutri- 
tion are  unfolded.  The  nutrition  of  a  foetus  and  de- 
velopment of  an  egg  proceed  in  a  totally  different 
manner  from  that  of  an  animal  which  is  separated 
from  its  parent ;  the  exclusion  of  air  does  not  en- 
danger the  life  of  the  foetus,  but  would  certainly 
cause  the  death  of  the  independent  animal.  In  the 
same  manner,  pure  water  is  more  advantageous  to 
the  growth  of  a  young  plant,  than  that  containing 
carbonic  acid,  but  after  a  month  the  reverse  is  the 
case. 

The  formation  of  sugar  in  maple-trees  does  not 
take  place  in  the  roots,  but  in  the  woody  substance 
of  the  stem.  The  quantity  of  sugar  in  the  sap  aug- 
ments until  it  reaches  a  certain  height  in  the  stem 
of  the  plant,  above  which  point  it  remains  stationary. 

Just  as  germinating^  barley  produces  a  substance 
which,  in  contact  with  starch,  causes  it  to  lose  its 
insolubility  and  to  become  sugar,  so  in  the  roots  of 
the  maple,  at  the  commencement  of  vegetation,  a 
substance  must  be  formed,  which,  being  dissolved  in 
water,  permeates  the  wood  of  the  trunk,  and  con- 
verts into  sugar  the  starch,  or  whatever  it  may  be, 
which  it  finds  deposited  there.  It  is  certain,  that 
when  a  hole  is  bored  into  the  trunk  of  a  maple-tree 
just  above  its  roots,  filled  with  sugar,  and  then  closed 
again,  the  sugar  is  dissolved  by  the  ascending  sap. 
It  is  further  possible  that  this  sugar  maybe  disposed 
of  in  the  same  manner  as  that  formed  in  the  trunks ; 
at  all  events  it  is  certain,  that  the  introduction  of  it 
does  not  prevent  the  action  of  the  juice  upon  the 
starch,  and  since  the  quantity  of  the  sugar  present  is 
now  greater  than  can  be  exhausted  by  the  leaves 
and  buds,  it  is  excreted  from  the  surface  of  the 
leaves  or  bark.  Certain  diseases  of  trees,  for  exam- 
ple that  called  honey-dew,  evidently  depend  on  tbe 
want  of  the  due  proportion  between  the  quantity  of 
the  azotized  and  that  of  the  unazotized  substances 
which  are  applied  to  them  as  nutriment. 

12^ 


138  THE  ART  OF  CULTURE. 

In  whatever  form,  therefore,  we  supply  plants  with 
those  substances  which  are  the  products  of  their 
own  action,  in  no  instance  do  they  appear  to  have 
any  effect  upon  their  growth,  or  to  replace  what  they 
have  lost.  Sugar,  gum,  and  starch,  are  not  food  for 
plants,  and  the  same  must  be  said  of  humic  acid, 
which  is  so  closely  allied  to  them  in  composition. 

If  now  we  direct  our  attention  to  the  particular 
organs  of  a  plant,  we  find  every  fibre  and  every 
particle  of  wood  surrounded  by  a  juice  containing 
an  azotized  matter;  while  the  starch,  granules,  and 
sugar,  are  enclosed  in  cells  formed  of  a  substance 
containing  nitrogen.  Indeed  everywhere,  in  all  the 
juices  of  the  fruits  and  blossoms,  we  find  a  substance 
destitute  of  nitrogen,  accompanied  by  one  which 
contains  that  element. 

The  wood  of  the  stem  cannot  be  formed,  quasi 
wood,  in  the  leaves,  but  another  substance  must  be 
produced  which  is  capable  of  being  transformed  into 
wood.  This  substance  must  be  in  a  state  of  solution, 
and  accompanied  by  a  compound  containing  nitro- 
gen ;  it  is  very  probable  that  the  wood  and  the 
vegetable  gluten,  the  starch  granules  and  the  cells 
containing  them,  are  formed  simultaneously,  and  in 
this  case  a  certain  fixed  proportion  between  them 
would  be  a  condition  necessary  for  their  production. 

According  to  this  view,  the  assimilation  of  the 
substances  generated  in  the  leaves  wnll  [cceteris 
paribus^  depend  on  the  quantity  of  nitrogen  con- 
tained in  the  food.  When  a  sufficient  quantity  of 
nitrogen  is  not  present  to  aid  in  the  assimilation  of 
the  substances  which  do  not  contain  it,  these  sub- 
stances will  be  separated  as  excrements  from  the 
bark,  roots,  leaves,  and  branches.  The  exudations 
of  mannite,  gum,  and  sugar,  in  strong  and  healthy 
plants  cannot  be  ascribed  to  any  other  cause.* 

'*  M.  Trapp  in  Giessen  possesses  a  Clerodendron  fragrans,  which 
grows  in  the  house,  and  exudes  on  the  surface  of  its  leaves  in  Sep- 
tember large  colorless  drops  of  sugar-candy,  which  form  regular  crys- 
tals upon  drying; — I  am  not  aware  whether  the  juice  of  this  plant 


CONDITIONS  ESSENTIAL  TO  NUTRITION.  139 

Analogous  phenomena  are  presented  by  the  pro- 
cess of  digestion  in  the  human  organism.  In  order 
that  the  loss  which  every  part  of  the  body  sustains 
by  the  processes  of  respiration  and  perspiration  may 
be  restored  to  it,  the  organs  of  digestion  require  to 
be  supplied  with  food,  consisting  of  substances  con- 
taining nitrogen,  and  of  others  destitute  of  it,  in 
definite  proportions.  If  the  substances  which  do 
not  contain  nitrogen  preponderate,  either  they  will 
be  expended  in  the  formation  of  fat,  or  they  will 
pass  unchanged  through  the  organism.  This  is  par- 
ticularly observed  in  those  people  who  live  almost 
exclusively  upon  potatoes ;  their  excrements  contain 
a  large  quantity  of  unchanged  granules  of  starch, 
of  which  no  trace  can  be  detected  when  gluten  or 
flesh  is  taken  in  proper  proportions,  because  in  this 
case  the  starch  has  been  rendered  capable  of  assim- 
ilation. Potatoes,  which  when  mixed  with  hay  alone 
are  scarcely  capable  of  supporting  the  strength  of  a 
horse,  form  with  bread  and  oats  a  strong  and  whole- 
some fodder. 

It  will  be  evident  from  the  preceding  considera- 
tions, that  the  products  generated  by  a  plant  may 
vary  exceedingly,  according  to  the  substances  given 
it  as  food.  A  superabundance  of  carbon  in  the  state 
of  carbonic  acid  conveyed  through  the  roots  of 
plants,  without  being  accompanied  by  nitrogen,  can- 
not be  converted  either  into  gluten,  albumen,  wood, 
or  any  other  component  part  of  an  organ ;  but  either 
it  will  be  separated  in  the  form  of  excrements,  such 
as  sugar,  starch,  oil,  wax,  resin,  mannite,*  or  gum, 
or  these  substances  will  be  deposited  in  greater  or 
less  quantity  in  the  wide  cells  and  vessels. 

contains  sugar.  Professor  Redtenbacher,  of  Prague,  informs  me  that 
he  has  analyzed  the  crystals,  and  found  them  to  be  perfectly  pure 
sugar.  — Ed. 

*  Mannite  forms  the  greater  part  of  manna.  It  is  found  in  the 
juices  of  several  fruits,  in  the  fermented  juice  of  beet-root,  carrots, 
onions,  &c. ;  it  is  also  obtained  in  small  quantity  when  starch  is 
transformed  into  grape  sugar  by  boiling  with  dilute  sulphuric  acid. 
It  crystallizes  in  prisms,  is  faintly  sweet,  soluble  in  water  and  hot 
alcohol.  Its  aqueous  solution  cannot  be  made  to  undergo  the  vinous 
fermentation.     Its  formula  is  Ce  H7  Oe. 


140  THE  ART  OF  CULTURE. 

The  quantity  of  gluten,  vegetable  albumen,  and 
mucilage,  will  augment  when  plants  are  supplied 
with  an  excess  of  food  containing  nitrogen ;  and 
ammoniacal  salts  will  remain  in  the  sap,  when,  for 
example,  in  the  culture  of  the  beet,  we  manure  the 
soil  with  a  highly  nitrogenous  substance,  or  when 
we  suppress  the  functions  of  the  leaves  by  removing 
them  from  the  plant. 

We  know  that  the  ananas  is  scarcely  eatable  in 
its  wild  state,  and  that  it  shoots  forth  a  great  quan- 
tity of  leaves  when  treated  with  rich  animal  manure, 
without  the  fruit  on  that  account  acquiring  a  large 
amount  of  sugar ;  that  the  quantity  of  starch  in 
potatoes  increases  when  the  soil  contains  much 
humus,  but  decreases  when  the  soil  is  manured  with 
strong  animal  manure,  although  then  the  number  of 
cells  increases,  the  potatoes  acquiring  in  the  first 
case  a  mealy,  in  the  second  ^  soapy,  consistence. 
Beet-roots  taken  from  a  barren,  sandy  soil  contain 
a  maximum  of  sugar,  and  no  ammoniacal  salts  ;  and 
the  Teltowa  parsnep  loses  its  mealy  state  in  a 
manured  land,  because  there  all  the  circumstances 
necessary  for  the  formation  of  cells  are  united.* 

An  abnormal  f  production  of  certain  component 
parts  of  plants  presupposes  a  power  and  capability 
of  assimilation  to  which  the  most  powerful  chemical 
action  cannot  be  compared.  The  best  idea  of  it  may 
be  formed  by  considering  that  it  surpasses  in  power 
the  strongest  galvanic  battery,  with  which  we  are 
not  able  to  separate  the  oxygen  from  carbonic  acid. 
The  affinity  of  chlorine  for  hydrogen,  and  its  power 
to   decompose   water    under    the    influence  of   light 

*  Children  fed  upon  arrow-root,  salep,  or  indeed  any  kind  of  amyla- 
ceous food,  which  does  not  contain  ingredients  fitted  for  the  formation 
of  bones  and  muscles,  become  fat,  and  acquire  much  embonpoint;  their 
limbs  appear  full,  but  they  do  not  acquire  strength,  nor  are  their  organs 
properly  developed. —  L. 

t  Abnormal^  (Lat.  ab,  from,  and  norma,  a  rule,)  Any  thing  without, 
or  contrary  to,  system  or  rule.  In  botany,  if  a  flower  has  five  petals, 
the  rule  is,  that  it  should  have  the  same  number  of  stamens,  or  some 
regular  multiple  of  that  number ;  if  it  has  only  four  or  six  stamens, 
the  flower  is  abnormal. 


EFFECT  OF  LIGHT  ON  CHEMICAL  COMBINATION.  141 

and  set  at  liberty  its  oxygen,  cannot  be  considered 
as  at  all  equalling  the  power  and  energy  with  which 
a  leaf  separated  from  a  plant  decomposes  the  car- 
bonic acid  which  it  absorbs. 

The  common  opinion,  that  only  the  direct  solar 
rays  can  effect  the  decomposition  of  carbonic  acid 
in  the  leaves  of  plants,  and  that  reflected  or  diffused 
light  does  not  possess  this  property,  is  wholly  an 
error,  for  exactly  the  same  constituents  are  generated 
in  a  number  of  plants,  whether  the  direct  rays  of 
the  sun  fall  upon  them,  or  whether  they  grow  in  the 
,  shade.  They  require  light,  and  indeed  sunlight, 
but  it  is  not  necessary  that  the  direct  rays  of  the 
sun  reach  them.  Their  functions  certainly  proceed 
with  greater  intensity  and  rapidity  in  sunshine  than 
in  the  diffused  light  of  day ;  but  there  is  nothing 
more  in  this  than  the  similar  action  which  light 
exercises  on  ordinary  chemical  combinations ;  it 
merely  accelerates  in  a  greater  or  less  degree  the 
action  already  subsisting. 

Thus  chlorine  *  and  hydrogen  combining  form  muri- 
atic (hydrochloric)  acid.  This  combination  is  effected 
in  a  few  hours  in  common  daylight,  but  it  ensues  in- 
stantly, with  a  violent  explosion,  under  exposure  to 
the  direct  solar  rays,  whilst  not  the  slightest  change 
in  the  two  gases  takes  place  in  perfect  darkness. 
When  the  liquid  hydrocarburet  of  chlorine,  resulting 
from  the  union  of  the  olefiant  gasf  of  the  associated 

*  Chlorine  is  a  gas  named  from  its  green  color  ;  it  was  formerly 
called  oxymuriatic  acid.  It  has  not  been  decomposed.  It  is  one  of  the 
most  suffocating  of  the  gases,  and  highly  irritating,  even  when  much 
diluted  with  air.  It  is  largely  absorbed  by  water,  and  the  solution  has 
the  properly  of  bleaching.  Its  solution  in  water  cannot  be  kept  un- 
changed, as  the  chlorine  unites  to  the  hydrogen  of  the  water  and 
forms  muriatic  or  hydrochloric  acid. 

Bleaching  salts  are  formed  by  exposing  lime  to  an  atmosphere  of 
chlorine.  Chlorine  is  useful  for  removing  offensive  odors.  A  few 
table  spoonfuls  of  bleaching  powder,  sprinkled  occasionally  in  privies, 
and  in  larger  quantities  upon  heaps  of  offensive  substances,  upon  the 
floors  of  slaughter-houses,  &-c.  will  destroy  the  unpleasant  odor,  and 
at  the  same  time  add  to  the  value  of  the  manure. 

For  description  of  chlorine,  and  the  method  of  procuring  it,  see 
Webster's  Chemistry^  3d  edit,  p    180. 

i  One  of  the  compounds  of  hydrogen  and  carbon. 


142  THE  ART  OF  CULTURE. 

Dutch  chemists  with  chlorine,  is  exposed  in  a  vessel 
with  chlorine  gas  to  the  direct  solar  rays,  chloride 
of  carbon  is  immediately  produced ;  but  the  same 
compound  can  be  obtained  with  equal  facility  in  the 
diffused  light  of  day,  a  longer  time  only  being  re- 
quired. When  this  experiment  is  performed  in  the 
way  first  mentioned,  two  products  only  are  observed 
(muriatic  acid  and  perchloride  of  carbon) ;  whilst  by 
the  latter  method  a  class  of  intermediate  bodies  are 
produced,  in  which  the  quantity  of  chlorine  con- 
stantly augments,  until  at  last  the  whole  liquid 
hydrocarburet  of  chlorine  is  converted  into  the  same 
two  products  as  in  the  first  case.  Here,  also,  not 
the  slightest  trace  of  decomposition  takes  place  in 
the  dark.  Nitric  acid  is  decomposed  in  common 
daylight  into  oxygen,  and  peroxide  of  nitrogen;  and 
chloride  of  silver  becomes  black  in  the  diffused  light 
of  day,  as  well  as  in  the  direct  solar  rays;  —  in 
short,  all  actions  of  a  similar  kind  proceed  in  the 
same  way  in  diffused  light  as  well  as  in  the  solar 
light,  the  only  difference  consisting  in  the  time  in 
which  they  are  effected.  It  cannot  be  otherwise  in 
plants,  for  the  mode  of  their  nutriment  is  the  same 
in  all,  and  their  component  substances  afford  proof 
that  their  food  has  suffered  absolutely  the  same 
change,  whether  they  grow  in  the  sunshine  or  in  the 
shade. 

,  All  the  carbonic  acid,  therefore,  which  we  supply 
to  a  plant  will  undergo  a  transformation,  provided 
its  quantity  be  not  greater  than  can  be  decomposed 
by  the  leaves.  We  know,  that  an  excess  of  carbonic 
acid  kills  plants,  but  we  know  also  that  nitrogen  to 
a  certain  degree  is  not  essential  for  the  decomposi- 
tion of  carbonic  acid.  All  the  experiments  hitherto 
instituted  prove,  that  fresh  leaves  placed  in  water 
impregnated  with  carbonic  acid,  and  exposed  to  the 
influence  of  solar  light,  emit  oxygen  gas,  whilst  the 
carbonic  acid  disappears.  Now  in  these  experiments 
no  nitrogen  is  supplied  at  the  same  time  with  the  car- 
bonic acid;  hence  no  other  conclusion  can  be  drawn 


IMPORTANCE  OF  AGRICULTURE.  143 

from  them  than  that  nitrogen  is  not  necessary  for 
the  decomposition  of  carbonic  acid,  —  for  the  exer- 
cise, therefore,  of  one  of  the  functions  of  plants. 
And  yet  the  presence  of  a  substance  containing  this 
element  appears  to  be  indispensable  for  the  assimila- 
tion of  the  products  newly  formed  by  the  decompo- 
sition of  the  carbonic  acid,  and  their  consequent 
adaptation  for  entering  into  the  composition  of  the 
different  organs. 

The  carbon  abstracted  from  the  carbonic  acid 
acquires  in  the  leaves  a  new  form,  in  which  it  is 
soluble  and  transferable  to  all  parts  of  the  plant. 
In  this  new  form  the  carbon  aids  in  constituting 
several  new  products  ;  these  are  named  sugar  when 
they  possess  a  sweet  taste,  gum  or  mucilage  when 
tasteless,  and  excrementitious  matters  when  expelled 
by  the  roots. 

Hence  it  is  evident,  that  the  quantity  and  quality 
of  the  substances  generated  by  the  vital  processes  of 
a  plant  will  vary  according  to  the  proportion  of  the 
different  kinds  of  food  with  which  it  is  supplied. 
The  development  of  every  part  of  a  plant  in  a  free 
and  uncultivated  state  depends  on  the  amount  and 
nature  of  the  food  afforded  to  it  by  the  spot  on 
which  it  grows.  A  plant  is  developed  on  the  most 
sterile  and  unfruitful  soil  as  well  as  on  the  most 
luxuriant  and  fertile,  the  only  difference  which  can 
be  observed  being  in  its  height  and  size,  in  the  num- 
ber of  its  twigs,  branches,  leaves,  blossoms,  and 
fruit.  Whilst  the  individual  organs  of  a  plant  in- 
crease on  a  fertile  soil,  they  diminish  on  another 
where  those  substances  which  are  necessary  for  their 
formation  are  not  so  bountifully  supplied ;  and  the 
proportion  of  the  constituents  which  contain  nitrogen 
and  of  those  which  do  not  in  plants  varies  with  the 
amount  of  nitrogenous  matters  in  their  food. 

The  development  of  the  stem,  leaves,  blossoms, 
and  fruit  of  plants  is  dependent  on  certain  con- 
ditions, the  knowledge  of  which  enables  us  to  ex- 
ercise some  influence  on  their  internal  constituents 


144  THE  ART  OF  CULTURE. 

as  well  as  on  their  size.  It  is  the  duty  of  the  natu- 
ral philosopher  to  discover  what  these  conditions 
are ;  for  the  fundamental  principles  of  agriculture 
must  be  based  on  a  knowledge  of  them.  There  is 
no  profession  which  can  be  compared  in  importance 
with  that  of  agriculture,  for  to  it  belongs  the  pro- 
duction of  food  for  man  and  animals ;  on  it  depends 
the  welfare  and  development  of  the  whole  human 
species,  the  riches  of  states,  and  all  commerce. 
There  is  no  other  profession  in  which  the  applica- 
tion of  correct  principles  is  productive  of  more  bene- 
ficial effects,  or  is  of  greater  and  more  decided  in- 
fluence. Hence  it  appears  quite  unaccountable,  that 
we  may  vainly  search  for  one  leading  principle  in  the 
writings  of  agriculturists  and  vegetable  physiologists. 

The  methods  employed  in  the  cultivation  of  land 
are  different  in  every  country,  and  in  every  district ; 
and  when  we  inquire  the  causes  of  these  differences, 
we  receive  the  answer,  that  they  depend  upon  cir- 
cumstances. [Les  cir Constances  font  les  assolements.) 
No  answer  could  show  ignorance  more  plainly,  since 
no  one  has  ever  yet  devoted  himself  to  ascertain 
what  these  circumstances  are.  Thus  also  when  we 
inquire  in  what  manner  manure  acts,  we  are  answered 
by  the  most  intelligent  men,  that  its  action  is  covered 
by  the  veil  of  Isis ;  and  when  we  demand  further 
what  this  means,  we  discover  merely  that  the  excre- 
ments of  men  and  animals  are  supposed  to  contain 
an  incomprehensible  something  which  assists  in  the 
nutrition  of  plants,  and  increases  their  size.  This 
opinion  is  embraced  without  even  an  attempt  being 
made  to  discover  the  component  parts  of  manure, 
or  to  become  acquainted  with  its  nature."^ 

In  addition  to  the  general  conditions,  such  as  heat, 
light,  moisture,  and  the  component  parts  of  the  atmo- 
sphere, which  are  necessary  for  the  growth  of  all 
plants,  certain  substances  are   found  to  exercise   a 

*  This  statement  is  now  somewhat  too  general;  both  in  this  country 
and  in  Great  Britain  agriculture  has  received  important  aid  from  the 
labors  of  chemists  and  physiologists. 


OBJECT  OF  AGRICULTURE.  145 

peculiar  influence  on  the  development  of  particular 
families.  These  substances  either  are  already  con- 
tained in  the  soil,  or  are  supplied  to  it  in  the  form 
of  the  matters  known  under  the  general  name  of 
manure.  But  what  does  the  soil  contain,  and  what 
are  the  components  of  the  substances  used  as  ma- 
nure ?  Until  these  points  are  satisfactorily  deter- 
mined, a  rational  system  of  agriculture  cannot  exist. 
The  power  and  knowledge  of  the  physiologist,  of  the 
agriculturist  and  chemist,  must  be  united  for  the 
complete  solution  of  these  questions  ;  and  in  order 
to  attain  this  end,  a  commencement  must  be  made. 

The  general  object  of  agriculture  is  to  produce  in 
the  most  advantageous  manner  certain  qualities,  or 
a  maximum  size,  in  certain  parts  or  organs  of  par- 
ticular plants.  Now,  this  object  can  be  attained 
only  by  the  application  of  those  substances  which 
we  know  to  be  indispensable  to  the  development  of 
these  parts  or  organs,  or  by  supplying  the  conditions 
necessary  to  the  production  of  the  qualities  desired. 

The  rules  of  a  rational  system  of  agriculture  should 
enable  us,  therefore,  to  give  to  each  plant  that 
which  it  requires  for  the  attainment  of  the  object  in 
view. 

The  special  object  of  agriculture  is  to  obtain  an 
abnormal  development  and  production  of  certain 
parts  of  plants,  or  of  certain  vegetable  matters^ 
which  are  employed  as  food  for  man  and  animals,  or 
for  the  purpose  of  industry. 

The  means  employed  for  effecting  these  two  pur-^ 
poses  are  very  different.  Thus  the  mode  of  culture^ 
employed  for  the  purpose  of  procuring  fine  pliable 
straw  for  Florentine  hats,  is  the  very  opposite  to 
that  which  must  be  adopted  in  order  to  produce  a 
maximum  of  corn  from  the  same  plant.  Peculiar 
methods  must  be  used  for  the  production  of  nitrogen 
in  the  seeds,  others  for  giving  strength  and  solidity 
to  the  straw,  and  others  again  must  be  followed 
when  we  wish  to  give  such  strength  and  solidity  to 
13 


146  THE  ART  OF  CULTURE. 

the  straw  as  will  enable  it  to  bear  the/weight  of  the 
ears. 

We  must  proceed  in  the  culture  of  plants  in  pre- 
cisely the  same  manner  as  we  do  in  the  fattening 
of  animals.  The  flesh  of  the  stag  and  roe,  or  of 
wild  animals  in  general,  is  quite  devoid  of  fat,  like 
the  muscular  flesh  of  the  Arab ;  or  it  contains  only 
small  quantities  of  it.  The  production  of  flesh  and 
fat  may  be  artificially  increased;  all  domestic  ani- 
mals, for  example,  contain  much  fat.  We  give  food 
to  animals,  which  increases  the  activity  of  certain 
organs,  and  is  itself  capable  of  being  transformed 
into  fat.  We  add  to  the  quantity  of  food  or  we 
lessen  the  processes  of  respiration  and  perspiration 
by  preventing  motion.  The  conditions  necessary  to 
effect  this  purpose  in  birds  are  diff"erent  from  those 
in  quadrupeds ;  and  it  is  well  known  that  charcoal 
powder  produces  such  an  excessive  growth  of  the 
liver  of  a  goose,  as  at  length  causes  the  death  of  the 
animal. 

The  increase  or  diminution  of  the  vital  activity  of 
vegetables  depends  only  on  heat  and  solar  light, 
which  we  have  not  arbitrarily  at  our  disposal :  all 
that  we  can  do  is  to  supply  those  substances  which  are 
adapted  for  assimilation  by  the  power  already  present 
in  the  organs  of  the  plant.  But  what  then  are  these 
substances  ?  They  may  easily  be  detected  by  the  ex- 
amination of  a  soil,  which  is  always  fertile  in  given 
cosmical  and  atmospheric  conditions ;  for  it  is  evi- 
dent, that  the  knowledge  of  its  state  and  compo- 
sition must  enable  us  to  discover  the  circumstances 
under  which  a  sterile  soil  may  be  rendered  fertile. 
It  is  the  duty  of  the  chemist  to  explain  the  com- 
position of  a  fertile  soil,  but  the  discovery  of  its 
proper  state  or  condition  belongs  to  the  agricul- 
turist ;  our  present  business  lies  only  with  the  former. 

Arable  land  is  originally  formed  by  the  crumbling 
of  rocks,  and  its  properties  depend  on  the  nature 
of  their  principal  component  parts.     Sand,  clay,  and 


FERTILITY  OF  DIFFERENT  SOILS-  147 

lime,  are  the  names  given  to  the  principal  constitu- 
ents of  the  different  kinds  of  soil. 

Pure  sand  and  pure  limestones,  in  which  there  are 
no  other  inorganic  substances  except  siliceous  earth, 
carbonate  or  silicate  of  lime,  form  absolutely  barren 
soils.  But  argillaceous  earths  form  always  a  part 
of  fertile  soils.  Now  from  whence  come  the  argil- 
laceous earths  in  arable  land,  what  are  their  con- 
stituents, and  what  part  do  they  play  in  favoring 
vegetation  ?  They  are  produced  by  the  disintegra- 
tion of  aluminous  minerals  by  the  action  of  the 
weather ;  the  common  potash  and  soda  felspars, 
Labrador  spar,  mica,  and  the  zeolites,  are  the  most 
common  aluminous  earths,  which  undergo  this  change. 
These  minerals  are  found  mixed  with  other  sub- 
tances  in  granite,  gneiss,  mica-slate,  porphyry,  clay- 
slate,  grauw^acke,  and  the  volcanic  rocks,  basalt,  clink- 
stone, and  lava.  In  the  grauwacke,  we  have  pure 
quartz,  clay-slate,  and  lime  ;  in  the  sandstones,  quartz 
and  loam.  The  transition  limestone  and  the  dolo- 
mites contain  an  intermixture  of  clay,  felspar,  por- 
phyry, and  clay-slate ;  and  the  mountain  limestone 
is  remarkable  for  the  quantity  of  argillaceous  earths 
which  it  contains.  Jura  limestone  contains  3 — 20, 
that  of  the  Wurtemberg  Alps  45  —  50  per  cent,  of 
these  earths.  And  in  the  muschelkalk  and  the  cal- 
caire  grossier  they  exist  in  greater  or  less  quantity. 

It  is  known,  that  the  aluminous  minerals  are  the 
most  widely  diffused  on  the  surface  of  the  earth,  and 
as  we  have  already  mentioned,  all  fertile  soils,  or 
soils  capable  of  culture,  contain  alumina  as  an  inva- 
riable constituent.  There  must,  therefore,  be  some- 
thing in  aluminous  earth  which  enables  it  to  exercise 
an  influence  on  the  life  of  plants,  and  to  assist  in 
their  development.  The  property  on  which  this  de- 
pends is  that  of  its  invariably  containing  potash  and 
soda. 

Alumina  exercises  only  an  indirect  influence  on 
vegetation,  by  its  power  of  attracting  and  retaining 
water  and  ammonia ;   it  is  itself  very  rarely  found  in 


146  THE  ART  OF  CULTURE. 

the  straw  as  will  enable  it  to  bear  the  w^eight  of  the 
ears. 

We  must  proceed  in  the  culture  of  plants  in  pre- 
cisely the  same  manner  as  we  do  in  the  fattening 
of  animals.  The  flesh  of  the  stag  and  roe,  or  of 
wild  animals  in  general,  is  quite  devoid  of  fat,  like 
the  muscular  flesh  of  the  Arab ;  or  it  contains  only 
small  quantities  of  it.  The  production  of  flesh  and 
fat  may  be  artificially  increased;  all  domestic  ani- 
mals, for  example,  contain  much  fat.  We  give  food 
to  animals,  which  increases  the  activity  of  certain 
organs,  and  is  itself  capable  of  being  transformed 
into  fat.  We  add  to  the  quantity  of  food  or  we 
lessen  the  processes  of  respiration  and  perspiration 
by  preventing  motion.  The  conditions  necessary  to 
eflfect  this  purpose  in  birds  are  different  from  those 
in  quadrupeds ;  and  it  is  well  known  that  charcoal 
powder  produces  such  an  excessive  growth  of  the 
liver  of  a  goose,  as  at  length  causes  the  death  of  the 
animal. 

The  increase  or  diminution  of  the  vital  activity  of 
vegetables  depends  only  on  heat  and  solar  light, 
which  we  have  not  arbitrarily  at  our  disposal :  all 
that  we  can  do  is  to  supply  those  substances  which  are 
adapted  for  assimilation  by  the  power  already  present 
in  the  organs  of  the  plant.  But  what  then  are  these 
substances  1  They  may  easily  be  detected  by  the  ex- 
amination of  a  soil,  which  is  always  fertile  in  given 
cosmical  and  atmospheric  conditions ;  for  it  is  evi- 
dent, that  the  knowledge  of  its  state  and  compo- 
sition must  enable  us  to  discover  the  circumstances 
under  which  a  sterile  soil  may  be  rendered  fertile. 
It  is  the  duty  of  the  chemist  to  explain  the  com- 
position of  a  fertile  soil,  but  the  discovery  of  its 
proper  state  or  condition  belongs  to  the  agricul- 
turist ;  our  present  business  lies  only  with  the  former. 

Arable  land  is  originally  formed  by  the  crumbling 
of  rocks,  and  its  properties  depend  on  the  nature 
of  their  principal  component  parts.     Sand,  clay,  and 


FERTILITY  OF  DIFFERENT  SOILS-  147 

lime,  are  the  names  given  to  the  principal  constitu- 
ents of  the  different  kinds  of  soil. 

Pure  sand  and  pure  limestones,  in  which  there  are 
no  other  inorganic  substances  except  siliceous  earth, 
carbonate  or  silicate  of  lime,  form  absolutely  barren 
soils.  But  argillaceous  earths  form  always  a  part 
of  fertile  soils.  Now  from  whence  come  the  argil- 
laceous earths  in  arable  land,  what  are  their  con- 
stituents, and  what  part  do  they  play  in  favoring 
vegetation  ?  They  are  produced  by  the  disintegra- 
tion of  aluminous  minerals  by  the  action  of  the 
weather;  the  common  potash  and  soda  felspars, 
Labrador  spar,  mica,  and  the  zeolites,  are  the  most 
common  aluminous  earths,  which  undergo  this  change. 
These  minerals  are  found  mixed  with  other  sub- 
tances  in  granite,  gneiss,  mica-slate,  porphyry,  clay- 
slate,  grauwacke,  and  the  volcanic  rocks,  basalt,  clink- 
stone, and  lava.  In  the  grauwacke,  we  have  pure 
quartz,  clay-slate,  and  lime  ;  in  the  sandstones,  quartz 
and  loam.  The  transition  limestone  and  the  dolo- 
mites contain  an  intermixture  of  clay,  felspar,  por- 
phyry, and  clay-slate ;  and  the  mountain  limestone 
is  remarkable  for  the  quantity  of  argillaceous  earths 
which  it  contains.  Jura  limestone  contains  3 — 20, 
that  of  the  Wurtemberg  Alps  45  —  50  per  cent,  of 
these  earths.  And  in  the  miischelkalk  and  the  cal- 
caire  grossier  they  exist  in  greater  or  less  quantity. 

It  is  known,  that  the  aluminous  minerals  are  the 
most  widely  diffused  on  the  surface  of  the  earth,  and 
as  we  have  already  mentioned,  all  fertile  soils,  or 
soils  capable  of  culture,  contain  alumina  as  an  inva- 
riable constituent.  There  must,  therefore,  be  some- 
thing in  aluminous  earth  which  enables  it  to  exercise 
an  influence  on  the  life  of  plants,  and  to  assist  in 
their  development.  The  property  on  which  this  de- 
pends is  that  of  its  invariably  containing  potash  and 
soda. 

Alumina  exercises  only  an  indirect  influence  on 
vegetation,  by  its  power  of  attracting  and  retaining 
water  and  ammonia ;   it  is  itself  very  rarely  found  in 


150  THE  ART  OF  CULTURE. 

kinds  of  plants  grow  with  the  greatest  luxuriance. 
This  fertility  is  owing  to  the  alkalies  which  are  con- 
tained in  the  lava,  and  which  by  exposure  to  the 
weather  are  rendered  capable  of  being  absorbed  by 
plants.  Thousands  of  years  have  been  necessary  to 
convert  stones  and  rocks  into  the  soil  of  arable  land, 
and  thousands  of  years  more  will  be  requisite  for 
their  perfect  reduction,  that  is,  for  the  complete  ex- 
haustion of  their  alkalies. 

We  see  from  the  composition  of  the  water  in  riv- 
ers, streamlets,  and  springs,  how  little  rain-water  is 
able  to  extract  alkali  from  a  soil,  even  after  a  term 
of  years ;  this  water  is  generally  soft,  and  the  com- 
mon salt,  which  even  the  softest  invariably  contains, 
proves,  that  those  alkaline  salts,  which  are  carried 
to  the  sea  by  rivers  and  streams,  are  returned  again 
to  the  land  by  wind  and  rain. 

Nature  itself  shows  us  what  plants  require  at  the 
commencement  of  the  development  of  their  germs 
and  first  radicle  fibres.  Becquerel  has  shown,  that 
the  graminecB^  leguminoscB,  cruciferce,  cichoracece,  urn- 
bellifercBj  conifer ce,  and  ciicurbitacece  emit  acetic  acid 
during  germination.  A  plant  which  has  just  broken 
through  the  soil,  and  a  leaf  just  burst  open  from  the 
bud,  furnish  ashes  by  incineration,  which  contain  as 
much,  and  generally  more,  of  alkaline  salts  than  at 
any  period  of  their  life.  (De  Saussure.)  Now  we 
know  also,  from  the  experiments  of  Becquerel,  in  what 
manner  these  alkaline  salts  enter  young  plants  ;  the 
acetic  acid  formed  during  germination  is  diffused 
through  the  wet  or  moist  soil,  becomes  saturated 
with  lime,  magnesia,  and  alkalies,  and  is  again  ab- 
sorbed by  the  radicle  fibres  in  the  form  of  neutral 
salts.  After  the  cessation  of  life,  when  plants  are 
subjected  to  decomposition  by  means  of  decay  and 
putrefaction,  the  soil  receives  again  that  which  had 
been  extracted  from  it. 

Let  us  suppose,  that  a  soil  has  been  formed  by  the 
action  of  the  weather  on  the  component  parts  of 
granite,  grauwacke,  mountain  limestone,  or  porphy- 


DISINTEGRATION  OF  SOILS.  151 

ry,  and  that  nothing  has  vegetated  on  it  for  thou- 
sands of  years.  Now  this  soil  would  become  a  mag- 
azine of  alkalies  in  a  condition  favorable  for  their 
assimilation  by  the  roots  of  plants. 

The  interesting  experiments  of  Struve  have  proved 
that  water  impregnated  with  carbonic  acid  decom- 
poses rocks  which  contain  alkalies,  and  then  dis- 
solves ^  part  of  the  alkaline  carbonates.  It  is  evi- 
dent that  plants  also,  by  producing  carbonic  acid 
during  their  decay,  and  by  means  of  the  acids  which 
exude  from  their  roots  in  the  living  state,  contribute 
no  less  powerfully  to  destroy  the  coherence  of  rocks. 
Next  to  the  action  of  air,  water,  and  change  of  tem- 
perature, plants  themselves  are  the  most  powerful 
agents  in  effecting  the  disintegration  of  rocks. 

Air,  water,  and  the  change  of  temperature  prepare 
the  different  species  of  rocks  for  yielding  to  plants 
the  alkalies  which  they  contain.  A  soil  which  has 
been  exposed  for  centuries  to  all  the  influences  which 
affect  the  disintegration  of  rocks,  but  from  which  the 
alkalies  have  not  been  removed,  will  be  able  to  afford 
the  means  of  nourishment  to  those  vegetables  which 
require  alkalies  for  their  growth  during  many  years  ; 
but  it  must  gradually  become  exhausted,  unless  those 
alkalies  which  have  been  removed  are  again  replaced  ; 
a  period,  therefore,  will  arrive  when  it  will  be  neces- 
sary to  expose  it  from  time  to  time  to  a  further  dis- 
integration, in  order  to  obtain  a  new  supply  of  solu- 
ble alkalies.  For  small  as  is  the  quantity  of  alkali 
which  plants  require,  it  is  nevertheless  quite  indis- 
pensable for  their  perfect  development.  But  when 
one  or  more  years  have  elapsed  without  any  alkalies 
having  been  extracted  from  the  soil,  a  new  harvest 
may  be  expected. 

The  first  colonists  of  Virginia  found  a  country  the 
soil  of  which  was  similar  to  that  mentioned  above ; 
harvests  of  wheat  and  tobacco  were  obtained  for  a 
century  from  one  and  the  same  field,  without  the  aid 
of  manure ;  but  now  whole  districts  are  converted 
into  unfruitful  pasture-land,  which  without  manure 


152  THE  ART  OF  CULTURE. 

produces  neither  wheat  nor  tobacco.  From  every 
acre  of  this  land  there  were  removed  in  the  space 
of  one  hundred  years  13,200  lbs.  of  alkalies  in 
leaves,  grain,  and  straw ;  it  became  unfruitful,  there- 
fore, because  it  was  deprived  of  every  particle  of 
alkali,  which  had  been  reduced  to  a  soluble  state, 
and  because  that  which  was  rendered  soluble  again 
in  the  space  of  one  year  was  not  sufficient  to  satisfy 
the  demands  of  the  plants.  Almost  all  the  culti- 
vated land  in  Europe  is  in  this  condition;  fallow  is 
the  term  applied  to  land  left  at  rest  for  further 
disintegration.  It  is  the  greatest  possible  mistake 
to  suppose  that  the  temporary  diminution  of  fertility 
in  a  soil  is  owing  to  the  loss  of  humus ;  it  is  the 
mere  consequence  of  the  exhaustion  of  the  alkalies. 

Let  us  consider  the  condition  of  the  country 
around  Naples,  which  is  famed  for  its  fruitful  corn- 
land  ;  the  farms  and  villages  are  situated  from 
eighteen  to  twenty-four  miles  distant  from  one  an- 
other, and  between  them  there  are  no  roads,  and 
consequently  no  transportation  of  manure.  Now 
corn  has  been  cultivated  on  this  land  for  thousands 
of  years,  without  any  part  of  that  which  is  annually 
removed  from  the  soil  being  artificially  restored  to 
it.  How  can  any  influence  be  ascribed  to  humus 
under  such  circumstances,  when  it  is  not  even  known 
w^hether  humus  was  ever  contained  in  the  soil? 

The  method  of  culture  in  that  district  completely 
explains  the  permanent  fertility.  It  appears  very 
bad  in  the  eyes  of  our  agriculturists,  but  there  it  is 
the  best  plan  which  could  be  adopted.  A  field  is 
cultivated  once  every  three  years  and  is  in  the 
intervals  allowed  to  serve  as  a  sparing  pasture  for 
cattle.  The  soil  experiences  no  change  in  the  two 
years  during  which  it  there  lies  fallow,  further  than 
that  it  is  exposed  to  the  influence  of  the  weather, 
by  which  a  fresh  portion  of  the  alkalies  contained 
in  it  are  again  set  free  or  rendered  soluble.  The 
animals  fed  on  these  fields  yield  nothing  to  these 
soils    which    they  did    not  formerly  possess.      The 


COMPOSITION  OF  SOILS.  153 

weeds  upon  which  they  live  spring  from  the  soil, 
and  that  which  they  return  to  it  as  excrement  must 
always  be  less  than  that  which  they  extract.  The 
fields,  therefore,  can  have  gained  nothing  from  the 
mere  feeding  of  cattle  upon  them ;  on  the  contrary, 
the  soil  must  have  lost  some  of  its  constituents. 

Experience  has  shown  in  agriculture  that  wheat 
should  not  be  cultivated  after  wheat  on  the  same 
soil,  for  it  belongs  with  tobacco  to  the  plants  which 
exhaust  a  soil.  But  if  the  humus  of  a  soil  gives  it 
the  power  of  producing  corn,  how  happens  it  that 
wheat  does  not  thrive  in  many  parts  of  Brazil,  where 
the  soils  are  particularly  rich  in  this  substance,  or 
in  our  own  climate,  in  soils  formed  of  mouldered 
wood ;  that  its  stalk  under  these  circumstances 
attains  no  strength,  and  droops  prematurely?  The 
cause  is  this,  that  the  strength  of  the  stalk  is  due 
to  silicate  of  potash,  and  that  the  corn  requires 
phosphate  of  magnesia,  neither  of  which  substances 
a  soil  of  humus  can  aiford,  since  it  does  not  contain 
them;  the  plant  may,  indeed,  under  such  circum- 
stances, become  an  herb,  but  will  not  bear  fruit. 

Again,  how  does  it  happen  that  wheat  does  not 
flourish  on  a  sandy  soil,  and  that  a  calcareous  soil  is 
also  unsuitable  for  its  growth,  unless  it  be  mixed 
with  a  considerable  quantity  of  clay?*  It  is  because 
these  soils  do  not  contain  alkalies  in  sufficient  quan- 
tity, the  growth  of  wheat  being  arrested  by  this 
circumstance,  even  should  all  other  substances  be 
presented  in  abundance. 

It  is  not  mere  accident  that  only  trees  of  the  fir 
tribe  grow  on  the  sandstone  and  limestone  of  the 
Carpathian  mountains   and  the   Jura,  whilst  we  find 

*  In  consequence  of  these  remarks  in  the  former  edition  of  this 
work,  Professor  Wohler  of  Gottingen  has  made  several  accurate  analy- 
ses of  different  kinds  of  limestone  belonging  to  the  secondary  and 
tertiary  formations.  He  obtained  the  remarkable  result,  that  all  those 
limestones,  by  the  disintegration  of  which  soils  adapted  for  the  culture 
of  wheat  are  formed,  invariably  contain  a  certain  quantity  of  potash. 
The  same  observation  has  also  recently  been  made  by  M.  Kuhlmann 
of  Lille.  The  latter  observed  that  the  efflorescence  on  the  mortar  of 
walls  consists  of  the  carbonates  of  soda  and  potash. — L. 


154  THE  ART  OF  CULTURE. 

on  soils  of  gneiss,  mica-slate,  and  granite  in  Bavaria, 
of  clinkstone  on  the  Rhone,  of  basalt  in  Vogelsberge, 
and  of  clay-slate  on  the  Rhine  and  Eifel,  the  finest 
forests  of  other  trees,  which  cannot  be  produced  on 
the  sandy  or  calcareous  soils  upon  which  pines 
thrive.  It  is  explained  by  the  fact  that  trees,  the 
leaves  of  which  are  renewed  annually,  require  for 
their  leaves  six  or  ten  times  more  alkalies  than 
the  fir-tree  or  pine,  and  hence  when  they  are  placed  in 
soils  in  which  alkalies  are  contained  in  very  small 
quantity,  do  not  attain  maturity.^  When  we  see 
such  trees  growing  on  a  sandy  or  calcareous  soil  — 
the  red-beech,  the  service-tree,  and  the  wild-cherry  for 
example,  thriving  luxuriantly  on  limestone,  we  may 
be  assured  that  alkalies  are  present  in  the  soil,  for 
they  are  necessary  to  their  existence.  Can  we,  then, 
regard  it  as  remarkable  that  such  trees  should  thrive 
in  America,  on  those  spots  on  which  forests  of  pines 
which  have  grown  and  collected  alkalies  for  centu- 
ries, have  been  burnt,  and  to  which  the  alkalies  are 
thus  at  once  restored  ;  or  that  the  Spartium  sco'pari" 
um^  Erysimum  latifoliumj^  Blitum>  capitatum>,  Senecio 
viscosus,  plants  remarkable  for  the  quantity  of  alka- 
lies contained  in  their  ashes,  should  grow  with  the 
greatest  luxuriance  on  the  localities  of  conflagra- 
tions ?f 

Wheat  will  not  grow  on  a  soil  which  has  produced 
wormwood,  and,  vice  versa,  wormwood  does  not 
thrive  where  wheat  has  grown,  because  they  are 
mutually  prejudicial  by  appropriating  the  alkalies 
of  the  soil. 

One   hundred   parts  of  the    stalks  of  wheat   yield 

*  One  thousand  parts  of  the  dry  leaves  of  oaks  yielded  55  parts  of 
ashes,  of  which  24  parts  consisted  of  alkalies  soluble  in  water ;  the 
same  quantity  of  pine-leaves  gave  only  29  parts  of  ashes,  which  con- 
tain 4-6  parts  of  soluble  salts.     (De  Saussure.) 

t  After  the  great  fire  in  London,  large  quantities  of  the  Erysimum 
latifolium  were  observed  growing  on  the  spots  where  a  fire  had  taken 
place.  On  a  similar  occasion  the  Blitum  capitatum  was  seen  at  Copen- 
hagen, the  Senecio  viscosus  in  Nassau,  and  the  Spartium  scoparium  in 
Languedoc.  After  the  burnings  of  forests  of  pines  in  North  America, 
poplars  grew  on  the  same  soil.  —  L. 


COMPOSITION  OF  SOILS.  155 

15*5  parts  of  ashes  (H.  Davy) ;  the  same  quantity 
of  the  dry  stalks  of  barley,  8.54  parts  (Schrader)  ; 
and  one  hundred  parts  of  the  stalks  of  oats,  only 
4*42 ;  —  the  ashes  of  all  these  are  of  the  same  com- 
position. 

We  have  in  these  facts  a  clear  proof  of  what 
plants  require  for  their  growth.  Upon  the  same 
field,  which  will  yield  only  one  harvest  of  wheat,  two 
crops  of  barley  and  three  of  oats  may  be  raised. 

All  plants  of  the  grass  kind  require  silicate  of  pot- 
ash. Now  this  is  conveyed  to  the  soil,  or  rendered 
soluble  in  it,  by  the  irrigation  of  meadow^s.  The 
equisetacecB,  the  reeds  and  species  of  cane,  for  ex- 
ample, which  contain  such  large  quantities  of  silice- 
ous earth,  or  silicate  of  potash,  thrive  luxuriantly  in 
marshes,  in  argillaceous  soils,  and  in  ditches,  stream- 
lets, and  other  places  where  the  change  of  water 
renews  constantly  the  supply  of  dissolved  silica. 
The  amount  of  silicate  of  potash  removed  from  a 
meadow  in  the  form  of  hay  is  very  considerable.  We 
need  only  call  to  mind  the  melted  vitreous  mass 
found  on  a  meadow  between  Manheim  and  Heidel- 
berg after  a  thunder-storm.  This  mass  was  at  first 
supposed  to  be  a  meteor,  but  was  found  on  examina- 
tion (by  Gmelin)  to  consist  of  silicate  of  potash; 
a  flash  of  lightning  had  struck  a  stack  of  hay,  and 
nothing  was  found  in  its  place  except  the  melted 
ashes  of  the  hay. 

Potash  is  not  the  only  substance  necessary  for  the 
existence  of  most  plants;  indeed  it  has  been  already 
shown  that  the  potash  may  be  replaced  in  many 
cases  by  soda,  magnesia,  or  lime;  but  other  sub- 
stances besides  alkalies  are  required  to  sustain  the 
life  of  plants. 

Phosphoric  acid  has  been  found  in  the  ashes  of  all 
plants  hitherto  examined,  and  always  in  combination 
with  alkalies  or  alkaline  earths.*     Most  seeds  con- 

*  Professor  Connall  was  lately  kind  enough  to  show  me  about  half 
an  ounce  of  a  saline  powder,  which  had  been  taken  from  an  interstice 
in  the  body  of  a  piece  of  teak  timber.    It  consisted  essentially  of  phos- 


156  THE  ART  OF  CULTURE. 

tain  certain  quantities  of  phosphates.  In  the  seeds 
of  different  kinds  of  corn  particularly,  there  is  abun- 
dance of  phosphate  of  magnesia. 

Plants  obtain  their  phosphoric  acid  from  the  soil. 
It  is  a  constituent  of  all  land  capable  of  cultivation, 
and  even  the  heath  at  Liineburg  contains  it  in  ap- 
preciable quantity.  Phosphoric  acid  has  been  de- 
tected also  in  all  mineral  waters  in  which  its  pres- 
ence has  been  tested;  and  in  those  in  which  it  has 
not  been  found  it  has  not  been  sought  for.  The 
most  superficial  strata  of  the  deposits  of  sulphuret 
of  lead  (^galena)  contain  crystallized  phosphate  of 
lead  {^greeyilead  ore) ;  clay-slate,  which  forms  ex- 
tensive strata,  is  covered  in  many  places  with  crys- 
tals of  phosphate  of  alumina  ( Wavellite) ;  all  its 
fractured  surfaces  are  overlaid  with  it.  Phosphate 
of  lime  (^Apatite)  is  found  even  in  the  volcanic 
boulders  on  the  Laacher  See  in  the  Eifel,  near 
Andernach.* 

The  soil  in  which  plants  grow  furnishes  them  with 
phosphoric  acid,  and  they  in  turn  yield  it  to  animals, 
to  be  used  in  the  formation  of  their  bones,  and  of 
those  constituents  of  the  brain  which  contain  phos- 
phorus. Much  more  phosphorus  is  thus  afforded  to 
the  body  than  it  requires,  when  flesh,  bread,  fruit, 
and  husks  of  grain  are  used  for  food,  and  this  ex- 
cess is  eliminated  in  the  urine  and  the  solid  excre- 
ments. We  may  form  an  idea  of  the  quantity  of 
phosphate  of  magnesia  contained  in  grain,  when  we 
consider  that  the  concretions  in  the  csecum  of  horses 

phate  of  lime,  with  small  quantities  of  carbonate  of  lime  and  phosphate 
of  magnesia.  This  powder  had  been  sent  to  Sir  David  Brewster  from 
India,  with  the  assurance  that  it  was  the  same  substance  which  usually 
is  found  in  the  hollows  of  teak  timber.  It  has  long  been  known  that 
silica,  in  the  form  of  tabasheer,  is  secreted  by  the  bamboo ;  but  I  am 
not  aware  that  phosphates  have  been  found  in  the  same  condition. 
Without  more  precise  information,  we  must  therefore  suppose  that  they 
are  left  in  the  hollows  by  the  decay  of  the  wood.  Decay  is  a  slow 
process  of  combustion,  and  the  incombustible  ashes  must  remain  after 
the  organic  matter  has  been  consumed.  But  if  this  explanation  be  cor- 
rect, the  wood  of  the  teak-tree  must  contain  an  enormous  quantity  of 
earthy  phosphates. — Ed. 

*  See  the  analyses  of  soils  in  the  Appendix. 


THE  FERTILITY  OF  SOILS.  157 

consist  of  phosphate  of  magnesia  and  ammonia, 
which  must  have  been  obtained  from  the  hay  and  oats 
consumed  as  food.  Twenty-nine  of  these  stones 
were  taken  after  death  from  the  rectum  of  a  horse 
belonging  to  a  miller,  in  Eberstadt,  the  total  weight 
of  which  amounted  to  3*3  lbs. ;  and  Dr.  F.  Simon  has 
lately  described  a  similar  concretion  found  in  the 
horse  of  a  carrier,  which  weighed  1'6  lb. 

It  is  evident  that  the  seeds  of  corn  could  not  be 
formed  without  phosphate  of  magnesia,  which  is  one 
of  their  invariable  constituents;  the  plant  could  not 
under  such  circumstances  reach  maturity. 

Some  plants,  however,  extract  other  matters  from 
the  soil  besides  silica,  potash,  and  phosphoric  acid, 
which  are  essential  constituents  of  the  plants  ordi- 
narily cultivated. =^  These  other  matters,  we  must 
suppose,  supply,  in  part  at  least,  the  place  and  per- 
form the  functions  of  the  substances  just  named. 
We  may  thus  regard  common  salt,  sulphate  of  pot- 
ash, nitre,  chloride  of  potassium,  and  other  matters, 
as  necessary  constituents  of  several  plants. 

Clay-slate  contains  generally  small  quantities  of 
oxide  of  copper;  and  soils  formed  from  micaceous 
schist  contain  some  metallic  fluorides.  Now,  small 
quantities  of  these  substances  also  are  absorbed  into 
plants,  although  we  cannot  affirm  that  they  are 
necessary  to  them. 

It  appears  that  in  certain  cases  fluoride  of  calci- 
um t  may  take  the  place  of  the  phosphate  of  lime  in  the 
bones  and  teeth  ;f  at  least  it  is  impossible  otherwise 
to   explain    its   constant   presence  in   the   bones  of 

*  For  more  minute  information  regarding  soils  see  the  supplemen- 
tary chapter  at  the  end  of  Part  I. 

t  Fluorine  is  the  base  of  the  acid  contained  in  Fluor  or  Derbyshire 
spar ;  with  hydrogen  it  forms  the  hydrofluoric  acid.  The  acid  is  separ- 
ated by  heating  fluor  spar  with  sulphuric  acid,  and  is  distinguished  by 
its  power  of  corroding  glass,  and  of  uniting  with  its  silica.  Compounds 
of  Fluorine  are  called  Fluorides^  of  the  acid  Hydrofluates.  Calcium  is 
the  metallic  base  of  lime. 

\  The  earthy  parts  of  bones  are  composed  principally  of  the  phos- 
phate and  carbonate  of  lime  in  various  proportions,  variable  in  different 
animals,  and  mixed  with  small  quantities,  equally  variable,  of  phos- 

14 


158  THE  ART  OF  CULTURE. 

antediluvian  animals,  by  which  they  are  distinguished 
from  those  of  a  later  period.  The  bones  of  human 
skulls  found  at  Pompeii  contain  as  much  fluoric  acid 
as  those  of  animals  of  a  former  world,  for  if  they  be 
placed  in  a  state  of  powder  in  glass  vessels,  and 
digested  with  sulphuric  acid,  the  interior  of  the 
vessel  will,  after  twenty-four  hours,  be  found  power- 
fully corroded  (Liebig) ;  whilst  the  bones  and  teeth 
of  animals  of  the  present  day  contain  only  traces  of 
it.     (Berzelius.) 

De  Saussure  remarked,  that  plants  require  unequal 
quantities  of  the  component  parts  of  soils  in  different 
stages  of  their  development ;  an  observation  of  much 
importance  in  considering  the  growth  of  plants. 
Thus,  wheat  yielded  jjgg  of  ashes  a  month  before 
blossoming,  ^^§5  while  in  blossom,  and  j§§q  after  the 
ripening  of  the  seeds.     It  is  therefore  evident,  that 

phate  of  magnesia  and  fluate  of  lime.  By  acting  upon  calcined  bones 
with  sulphuric  acid  fluoric  acid  is  disengaged.  The  following  analyses 
of  the  bones  of  man  and  horned  cattle,  are  given  by  Berzelius. 

Human  bone.      Ox  bone. 

Cartilage  soluble  in  water,        .        .        .      32.17  >  33  30 

Vessels,        .         .        .        .         .        .         .     1*^3  \ 

Subphosphate,  and  a  little  fluate  of  lime,  . 

Carbonate  of  lime,  .... 

Phosphate  of  magnesia, 

Soda  and  very  little  muriate  of  soda, 

100.00  100.00 

The  bones  of  man  contain  three  times  as  much  carbonate  of  lime  as 
those  of  the  ox,  and  the  latter  are  richer  in  phosphate  of  lime  and 
magnesia  in  the  same  proportion. 

The  following  are  the  relative  proportions  of  phosphate  and  carbonate 
of  lime  in  bones  of  different  animals,  according  to  De  Barros. 

Phosphate  of  Lime.         Carbonate  of  Lime. 

Lion, 95.0  2.5 

Sheep,        ....        80.0  19.3 

Hen, 88.9  10.4 

Frog,          ....        95.2  2.4 

Fish, 91.9  5.3 

The  enamel  of  the  teeth  is  composed  of 

Human.  Ox. 

Phosphate  of  lime,       .        .        .    88.5  85.0 

Carbonate  of    ''         .         .         .         8.0  7.1 

Phosphate  of  magnesia,         .         .1.5  3.0 

Soda, 0.0  1.4 

Membrane,  alkali  and  water,        .     2.0  3.5 

100.0  100.0 


53.04 

11.30 

.    1.16 

1.20 

57.35 
3.85 
2.05 
3.45 

FALLOW-CROPS.  159 

wheat,  from  the  time  of  its  flowering,  restores  a  part 
of  its  organic  constituents  to  the  soil,  although  the 
phosphate  of  magnesia  remains  in  the  seeds. 

The  fallow-time,  as  we  have  already  shown,  is  that 
period  of  culture  during  which  land  is  exposed  to  a 
progressive  disintegration  by  means  of  the  influence 
of  the  atmosphere,  for  the  purpose  of  rendering  a 
certain  quantity  of  alkalies  capable  of  being  appro- 
priated by  plants. 

Now,  it  is  evident,  that  the  careful  tilling  of  fal- 
low-land must  increase  and  accelerate  this  disinte- 
gration. For  the  purpose  of  agriculture,  it  is  quite 
indifferent,  whether  the  land  is  covered  with  weeds, 
or  with  a  plant  which  does  not  abstract  the  potash 
inclosed  in  it.  Now  many  plants  in  the  family  of 
the  leguminosce  are  remarkable  on  account  of  the 
small  quantity  of  alkalies  or  salts  in  general  which 
they  contain;  the  Windsor  bean  (  Fzcm  Faba),  {ov 
example,  contains  no  free  alkalies,  and  not  one  per 
cent,  of  the  phosphates  of  lime  and  magnesia. 
(Einhof.)  The  bean  of  the  kidney 'he3.n*(^P has eohis 
vulgaris)  contains  only  traces  of  salts.  (Braconnot.) 
The  stem  of  Lucern  (Medicago  sativa)  contains  only 
0*83  per  cent.,  that  of  the  Lentil  (^Ervum  Lens) 
only  0-57  of  phosphate  of  lime  with  albumen. 
(Crome.)  Buck-wheat  dried  in  the  sun  yields  only 
0-681  per  cent,  of  ashes,  of  which  0*09  parts  are 
soluble  salts.     (Zenneck.)*     These  plants  belong  to 

*  The  small  quantity  of  phosphates  which  the  seeds  of  the  lentils, 
beans,  and  peas  contain,  must  be  the  cause  of  their  small  value  as 
articles  of  nourishment,  since  they  surpass  all  other  vegetable  food  in 
the  quantity  of  nitrogen  which  enters  into  their  composition.  But  as 
the  component  parts  of  the  bones  (phosphate  of  lime  and  magnesia) 
are  absent,  they  satisfy  the  appetite  without  increasing  the  strength. 
The  following  is  an  analysis  of  lentils  (Playfair).  6-092  grammes  lost 
0-972  grammes  of  water  at  212°.  0.566  grammes,  burned  with  oxide 
of  copper,  gave  0-910  grammes  carbonic  acid  and  0  336  grammes  of 
water.  The  lentils  on  combustion  with  oxide  of  copper,  yielded  a  gas, 
in  which  the  proportion  of  the  nitrogen  to  the  carbonic  acid  was 
asl:  16. 

Carbon        44  45 

Hydrogen     6-59 

Nitrogen       642 

Water  15  95 


160  THE  ART  OF  CULTURE. 

those  which  are  termed  fallow-crops,  and  the  cause 
wherefore  they  do  not  exercise  any  injurious  influ- 
ence on  corn  which  is  cultivated  immediately  after 
them  is,  that  they  do  not  extract  the  alkalies  of  the 
soil,  and  only  a  very  small  quantity  of  phosphates. 

It  is  evident  that  tw^o  plants  growing  beside  each 
other  will  mutually  injure  one  another,  if  they  with- 
draw the  same  food  from  the  soil.  Hence  it  is  not 
surprising  that  the  wild  chamomile  (^Matricaria 
Chamomilla)  and  Scotch  broom  (^Spartium  Scopa- 
rium)  impede  the  growth  of  corn,  when  it  is  con- 
sidered that  both  yield  from  7  to  7-43  per  cent,  of 
ashes,  which  contain  ^^  of  carbonate  of  potash.  The 
darnel  and  the  fleabane  (^Erigeron  acre)  blossom  and 
bear  fruit  at  the  same  time  as  corn,  so  that  when 
growing  mingled  with  it,  they  will  partake  of  the 
component  parts  of  the  soil,  and  in  proportion  to 
the  vigor  of  their  growth,  that  of  the  corn  must 
decrease ;  for  what  one  receives,  the  others  are 
deprived  of.  Plants  wdll,  on  the  contrary,  thrive 
beside  each  other,  either  when  the  substances  neces- 
sary for  their  growth  which  they  extract  from  the 
soil  are  of  different  kinds,  or  when  they  themselves 
are  not  both  in  the  same  stages  of  development  at 
the  same  time. 

On  a  soil,  for  example,  which  contains  potash,  both 
wheat  and  tobacco  may  be  reared  in  succession, 
because  the  latter  plant  does  not  require  phosphates, 
salts  which  are  invariably  present  in  wheat,  but  re- 
quires only  alkalies,  and  food  containing  nitrogen. 

According  to  the  analysis  of  Posselt  and  Reimann, 
10,000  parts  of  the  leaves  of  the  tobacco-plant  con- 
tain 16  parts  of  phosphate  of  lime,  8*8  parts  of 
silica,  and  no  magnesia ;  whilst  an  equal  quantity 
of  wheat  straw^  contains  47*3  parts,  and  the  same 
quantity  of  the  grain  of  wheat  99'45  parts  of  phos- 
phates.    (De  Saussure.) 

Now,  if  we  suppose  that  the  grain  of  wheat  is 
equal  to  half  the  weight  of  its  straw,  then  the  quan- 
tity of  phosphates  extracted  from  a  soil  by  the  same 


THE  ALTERNATION  OF  CROPS.  161 

weights  of  wheat  and  tobacco  must  be  as  97-7:  16. 
This  difference  is  very  considerable.  The  roots  of 
tobacco,  as  well  as  those  of  wheat,  extract  the  phos- 
phates contained  in  the  soil,  but  they  restore  them 
again,  because  they  are  not  essentially  necessary  to 
the  development  of  the  plant. 


CHAPTER   VIII. 

ON  THE  ALTERNATION  OF  CROPS. 

It  has  long  since  been  found  by  experience,  that 
the  growth  of  annual  plants  is  rendered  imperfect, 
and  their  crops  of  fruit  or  herbs  less  abundant,  by 
cultivating  them  in  successive  years  on  the  same 
soil,  and  that,  in  spite  of  the  loss  of  time,  a  greater 
quantity  of  grain  is  obtained  when  a  field  is  allowed 
to  lie  uncultivated  for  a  year.  During  this  interval 
of  rest,  the  soil,  in  a  great  measure,  regains  its 
original  fertility. 

It  has  been  further  observed,  that  certain  plants, 
such  as  peas,  clover,  and  flax,  thrive  on  the  same 
soil  only  after  a  lapse  of  years ;  whilst  others,  such 
as  hemp,  tobacco,  helianthus  tuberosus,  rye,  and  oats, 
may  be  cultivated  in  close  succession  when  proper 
manure  is  used.  It  has  also  been  found,  that  several 
of  these  plants  improve  the  soil,  whilst  others,  and 
these  are  the  most  numerous,  impoverish  or  exhaust 
it.  Fallow  turnips,  cabbage,  beet,  spelt,  summer 
and  winter  barley,  rye  and  oats,  are  considered  to 
belong  to  the  class  which  impoverish  a  soil ;  whilst 
by  wheat,  hops,  madder,  late  turnips,  hemp,  poppies, 
teasel,  flax,  weld,  and  licorice,  it  is  supposed  to  be 
entirely  exhausted. 

The  excrements  of  man  and  animals  have  been 
employed  from  the  earliest  times  for  the  purpose  of 
increasing  the  fertility  of  soils ;  and  it  is  completely 

established  by  all  experience,  that    they  restore   cer- 

14# 


162  THE  ALTERNATION  OF  CROPS. 

tain  constituents  to  the  soil,  which  are  removed  with 
the  roots,  fruit,  or  grain,  or  entire  plants  grown 
upon  it. 

But  it  has  been  observed,  that  the  crops  are  not 
always  abundant  in  proportion  to  the  quantity  of 
manure  employed,  even  although  it  may  have  been 
of  the  most  powerful  kind ;  that  the  produce  of 
many  plants,  for  example,  diminishes,  in  spite  of  the 
apparent  replacement  by  manure  of  the  substances 
removed  from  the  soil,  when  they  are  cultivated  on 
the  same  field  for  several  years  in  succession. 

On  the  other  hand  it  has  been  remarked,  that  a 
field  which  has  become  unfitted  for  a  certain  kind  of 
plants  was  not  on  that  account  unsuited  for  another; 
and  upon  this  observation,  a  system  of  agriculture 
has  been  gradually  founded,  the  principal  object  of 
which  is  to  obtain  the  greatest  possible  produce  with 
the  least  expense  of  manure. 

Now  it  was  deduced  from  all  the  foregoing  facts, 
that  plants  require  for  their  growth  different  con- 
stituents of  soil,  and  it  was  very  soon  perceived, 
that  an  alternation  of  the  plants  cultivated  main- 
tained the  fertility  of  a  soil  quite  as  well  as  leaving 
it  at  rest  or  fallow.  It  was  evident,  that  all  plants 
must  give  back  to  the  soil  in  which  they  grow  differ- 
ent proportions  of  certain  substances,  which  are  capa- 
ble of  being  used  as  food  by  a  succeeding  generation. 

But  agriculture  has  hitherto  never  sought  aid  from 
chemical  principles,  based  on  the  knowledge  of  those 
substances  w^hich  plants  extract  from  the  soil  on 
which  they  grow,  and  of  those  restored  to  the  soil 
by  means  of  manure.  The  discovery  of  such  prin- 
ciples \till  be  the  task  of  a  future  generation,  for 
what  can  be  expected  from  the  present,  which  recoils 
with  seeming  distrust  and  aversion  from  all  the 
means  of  assistance  offered  it  by  chemistry,  and 
which  does  not  understand  the  art  of  making  a 
rational  application  of  chemical  discoveries  ?  A 
future  generation,  however,  will  derive  incalculable 
advantage  from  these  means  of  help. 


THEORY  OF  ITS  USE.  163 

Of  all  the  views  which  have  been  adopted  regard- 
ing the  cause  of  the  favorable  effects  of  the  alter- 
nations of  crops,  that  proposed  by  M.  Decandolle 
alone  deserves  to  be  mentioned  as  resting  on  a  firm 
basis. 

Decandolle  supposes,  that  the  roots  of  plants 
imbibe  soluble  matter  of  every  kind  from  the  soil, 
and  thus  necessarily  absorb  a  number  of  substances 
which  are  not  adapted  to  the  purposes  of  nutrition, 
and  must  subsequently  be  expelled  by  the  roots,  and 
returned  to  the  soil  as  excrements.  Now  as  excre- 
ments cannot  be  assimilated  by  the  plant  which  eject- 
ed them,  the  more  of  these  matters  which  the  soil 
contains,  the  more  unfertile  must  it  be  for  the  plants 
of  the  same  species.  These  excrementitious  matters 
may,  however,  still  be  capable  of  assimilation  by 
another  kind  of  plants,  which  would  thus  remove 
them  from  the  soil,  and  render  it  again  fertile  for 
the  first.  And  if  the  plants  last  grown  also  expel 
substances  from  their  roots,  which  can  be  appropri- 
ated as  food  by  the  former,  they  w^ill  improve  the 
soil  in  two  ways. 

Now  a  great  number  of  facts  appear  at  first  sight 
to  give  a  high  degree  of  probability  to  this  view. 
Every  gardener  knows,  that  a  fruit-tree  cannot  be 
made  to  grow  on  the  same  spot  where  another  of  the 
same  species  has  stood ;  at  least  not  until  after  a 
lapse  of  several  years.  Before  new  vine-stocks  are 
planted  in  a  vineyard  from  which  the  old  have  been 
rooted  out,  other  plants  are  cultivated  on  the  soil 
for  several  years.  In  connexion  with  this  it  has 
been  observed,  that  several  plants  thrive  best  when 
growing  beside  one  another;  and,  on  the  contrary, 
that  others  mutually  prevent  each  other's  develop- 
ment. Whence  it  was  concluded,  that  the  beneficial 
influence  in  the  former  case  depended  on  a  mutual 
interchange  of  nutriment  between  the  plants,  and 
the  injurious  one  in  the  latter  on  a  poisonous  action 
of  the  excrements  of  each  on  the  other  respectively.* 

*  That  these  supposed  exudations  are  uniformly  more  or  less  injuri- 


164  THE  ALTERNATION  OF  CROPS. 

A  series  of  experiments  by  Macaire-Princep  gave 
great  weight  to  this  theory.  He  proved  beyond  all 
doubt,  that  many  plants  are  capable  of  emitting  ex- 
tractive matter  from  their  roots.  He  found  that  the 
excretions  were  greater  during  the  night  than  by 
day  (?),  and  that  the  water  in  which  plants  of  the 
family  of  the  Leguminosce  grew  acquired  a  brown 
color.  Plants  of  the  same  species  placed  in  water 
impregnated  with  these  excrements  were  impeded  in 
their  growth,  and  faded  prematurely,  whilst,  on  the 
contrary,  corn-plants  grew  vigorously  in  it,  and  the 
color  of  the  water  diminished  sensibly;  so  that  it 
appeared  as  if  a  certain  quantity  of  the  excrements 
of  the  Leguminosce  had  really  been  absorbed  by  the 
corn-plants.  These  experiments  afforded,  as  their 
main  result,  that  the  characters  and  properties  of  the 
excrements  of  different  species  of  plants  are  different 
from  one  another,  and  that  some  plants  expel  excre- 
mentitious  matter  of  an  acid  and  resinous  character ; 
others  mild  substances  resembling  gum.  The  former 
of  these,  according  to  Macaire-Princep,  may  be  re- 
garded as  poisonous,  the  latter  as  nutritious. 

The  experiments  of  Macaire-Princep  afford  posi- 
tive proof  that  the  roots,  probably  of  all  plants,  ex- 
pel matters,  which  cannot  be  converted  in  their  or- 
ganism either  into  woody  fibre,  starch,  vegetable  al- 
bumen, or  gluten,  since  their  expulsion  indicates  that 
they  are  quite  unfitted  for  this   purpose.     But  they 

ous  to  plants  of  similar  species,  has  been  inferred  from  the  fact,  that  a 
soil,  in  which  peach  or  apple  trees  have  grown,  is  unfit  for  young  shoots 
of  the  same  description,  so  as  to  render  it  a  necessary  rule  in  practice, 
that  a  piece  of  ground  should  be  occupied  by  forest  and  by  fruit  trees 
alternately. 

Reference  has  also  been  made  to  a  circumstance,  which  most  travel- 
lers in  the  United  States  have  remarked,  and  which  I  myself,  during 
my  tour  in  that  country,  had  frequent  opportunities  of  substantiating, 
namely,  that  where  a  forest  of  oak  or  of  maple  has  been  destroyed,  the 
trees,  that  are  apt  to  shoot  up  spontaneously  in  their  place,  are  of  the 
fir-tribe ;  whereas,  if  a  pine  forest  be  cut  down,  young  oaks  and  other 
allied  species  will  make  their  appearance  afterwards. — Daubeny's 
Lectures  on  Agriculture. 

For  an  account  of  experiments  on  this  subject  now  in  progress  at  Ox- 
ford, see  Appendix. 


THEORIES  OF  ITS  USE.  165 

cannot  be  considered  as  a  confirmation  of  the  theory 
of  Decandolle,  for  they  leave  it  quite  undecided 
whether  the  substances  were  extracted  from  the  soil, 
or  formed  by  the  plant  itself  from  food  received  from 
another  source.  It  is  certain,  that  the  gummy  and 
resinous  excrements  observed  by  Macaire-Princep 
could  not  have  been  contained  in  the  soil,  and  as  we 
know  that  the  carbon  of  a  soil  is  not  diminished  by 
culture,  but,  on  the  contrary,  increased,  we  must 
conclude  that  all  excrements  which  contain  carbon 
must  be  formed  from  the  food  obtained  by  plants 
from  the  atmosphere.  Now,  these  excrements  are 
compounds,  produced  in  consequence  of  the  trans- 
formations of  the  food,  and  of  the  new  forms  w^hich 
it  assumes  by  entering  into  the  composition  of  the 
various  organs. 

M.  Decandolle's  theory  is  properly  a  modification 
of  an  earlier  hypothesis,  which  supposed  that  the 
roots  of  different  plants  extracted  different  nutritive 
substances  from  the  soil,  each  plant  selecting  that 
which  was  exactly  suited  for  its  assimilation.  Ac- 
cording to  this  hypothesis,  the  matters  incapable  of 
assimilation  are  not  extracted  from  the  soil,  whilst 
M.  Decandolle  considers  that  they  are  returned  to  it 
in  the  form  of  excrements.  Both  views  explain  how 
it  happens  that  after  corn,  corn  cannot  be  raised 
with  advantage,  nor  after  peas,  peas  ;  but  they  do 
not  explain  how  a  field  is  improved  by  lying  fallow, 
and  this  in  proportion  to  the  care  with  which  it  is 
tilled  and  kept  free  from  weeds ;  nor  do  they  show 
how  a  soil  gains  carbonaceous  matter  by  the  cultiva- 
tion of  certain  plants  such  as  lucern  and  sainfoin. 

Theoretical  considerations  on  the  process  of  nutri- 
tion, as  well  as  the  experience  of  all  agriculturists, 
so  beautifully  illustrated  by  the  experiments  of  Ma- 
caire-Princep, leave  no  doubt  that  substances  are 
excreted  from  the  roots  of  plants,  and  that  these 
matters  form  the  means  by  which  the  carbon  received 
from  humus  in  the  early  period  of  their  growth  is 
restored  to  the  soil.     But  we  may  now  inquire  wheth- 


166  THE  ALTERNATION  OF  CROPS. 

er  these  excreraents,  in  the  state  in  which  they  are 
expelled,  are  capable  of  being  employed  as  food  by 
other  plants. 

The  excrements  of  a  carnivorous  animal  contain 
no  constituents  fitted  for  the  nourishment  of  another 
of  the  same  species  ;  but  it  is  possible  that  an  her- 
bivorous animal,  a  fish,  or  a  fowl,  might  find  in  them 
undigested  matters  capable  of  being  digested  in 
their  organism,  from  the  very  circumstance  of  their 
organs  of  digestion  having  a  different  structure. 
This  is  the  only  sense  in  which  we  can  conceive  that 
the  excrements  of  one  animal  could  yield  matter 
adapted  for  the  nutrition  of  another. 

A  number  of  substances  contained  in  the  food  of 
animals  pass  through  their  alimentary  organs  without 
change,  and  are  expelled  from  the  system ;  these  are 
excrements  but  not  excretions.  Now^  a  part  of  such 
excrementitious  matter  might  be  assimilated  in  pass- 
ing through  the  digestive  apparatus  of  another  ani- 
mal. The  organs  of  secretion  form  combinations  of 
which  only  the  elements  were,  contained  in  the  food. 
The  production  of  these  new  compounds  is  a  conse- 
quence of  the  changes  which  the  food  undergoes  in 
becoming  chyle  and  chyme,  and  of  the  further  trans- 
formations to  which  these  are  subjected  by  entering 
into  the  composition  of  the  organism.  These  mat- 
ters, likewise,  are  eliminated  in  the  excrements, 
which  must  therefore  consist  of  two  different  kinds 
of  substances,  namely,  of  the  indigestible  constitu- 
ents of  the  food,  and  of  the  new  compounds  formed 
by  the  vital  process.  The  latter  substances  have 
been  produced  in  consequence  of  the  formation  of 
fat,  muscular  fibre,  cerebral  and  nervous  substance, 
and  are  quite  incapable  of  being  converted  into  the 
same  substances  in  any  other  animal  organism. 

Exactly  similar  conditions  must  subsist  in  the  vi- 
tal processes  of  plants.  When  substances  which  are 
incapable  of  being  employed  in  the  nutrition  of  a 
plant  exist  in  the  matter  absorbed  by  its  roots,  they 
must  be  again  returned  to  the  soil.    Such  excrements 


CAUSES  OF  ITS  BENEFICIAL  INFLUENCE.  167 

might  be  serviceable  and  even  indispensable  to  the 
existence  of  several  other  plants.  But  substances 
that  are  formed  in  a  vegetable  organism  during  the 
process  of  nutrition,  which  are  produced,  therefore, 
in  consequence  of  the  formation  of  w^oody  fibre, 
starch,  albumen,  gum,  acids,  &c.,  cannot  again  serve 
in  any  other  plants  to  form  the  same  constituents  of 
vegetables. 

The  consideration  of  these  facts  enables  us  to  dis- 
tinguish the  difference  between  the  views  of  Decan- 
dolle  and  those  of  Macaire-Princep.  The  substances 
which  the  former  physiologist  viewed  as  excrements, 
belonged  to  the  soil ;  they  were  undigested  matters, 
which  although  not  adapted  for  the  nutrition  of  one 
plant  might  yet  be  indispensable  to  another.  Those 
matters,  on  the  contrary,  designated  as  excrements 
by  Macaire-Princep,  could  only  in  one  form  serve  for 
the  nutrition  of  vegetables.  It  is  scarcely  necessary 
to  remark,  that  this  excrementitious  matter  must  un- 
dergo a  change  before  another  season.  During  au- 
tumn and  winter  it  begins  to  suffer  a  change  from 
the  influence  of  air  and  water ;  its  putrefaction,  and 
at  length,  by  continued  contact  with  the  air,  which 
tillage  is  the  means  of  procuring,  its  decay  are  effect- 
ed ;  and  at  the  commencement  of  spring  it  has  be- 
come converted,  either  in  whole  or  in  part,  into  a 
substance  which  supplies  the  place  of  humus,  by  be- 
ing a  constant  source  of  carbonic  acid. 

The  quickness  with  which  this  decay  of  the  ex- 
crements of  plants  proceeds  depends  on  the  com- 
position of  the  soil,  and  on  its  greater  or  less  po- 
rosity. It  will  take  place  very  quickly  in  a  calcareous 
soil :  for  the  power  of  organic  excrements  to  attract 
oxygen  and  to  putrefy  is  increased  by  contact  with 
the  alkaline  constituents,  and  by  the  general  porous 
nature  of  such  kinds  of  soil,  which  freely  permit  the 
access,  of  air.  But  it  requires  a  longer  time  in  heavy 
soils  consisting  of  loam  or  clay. 

The  same  plants  can  be  cultivated  with  advantage 
on  one  soil  after  the  second  year,  but  in  others  not 


168  THE  ALTERNATION  OF  CROPS. 

until  the  fifth  or  ninth,  merely  on  account  of  the 
change  and  destruction  of  the  excrements,  which 
have  an  injurious  influence  on  the  plants  being  com- 
pleted in  the  one,  in  the  second  year;  in  the  others, 
not  until  the  ninth. 

In  some  neighborhoods  clover  will  not  thrive  till 
the  sixth  year,  in  others  not  till  the  twelfth ;  flax  in 
the  second  or  third  year.  All  this  depends  on  the 
chemical  nature  of  the  soil,  for  it  has  been  found  by 
experience,  that  in  those  districts  where  the  intervals 
at  which  the  same  plants  can  be  cultivated  with  ad- 
vantage are  very  long,  the  time  cannot  be  shortened 
even  by  the  use  of  the  most  powerful  manures.  The 
destruction  of  the  peculiar  excrements  of  one  crop 
must  have  taken  place  before  a  new  crop  can  be 
produced. 

Flax,  peas,  clover,  and  even  potatoes,  are  plants 
the  excrements  of  which,  in  argillaceous  soils,  re- 
quire the  longest  time  for  their  conversion  into 
humus ;  but  it  is  evident,  that  the  use  of  alkalies 
and  burnt  lime,  or  even  small  quantities  of  ashes 
which  have  not  been  lixiviated,  must  enable  a  soil 
to  permit  the  cultivation  of  the  same  plants  in  a 
much  shorter  time. 

A  soil  lying  fallow  owes  its  earlier  fertility,  in 
part,  to  the  destruction  or  conversion  into  humus  of 
the  excrements  contained  in  it,  which  is  effected 
during  the  fallow  season,  at  the  same  time  that  the 
land  is  exposed  to  a  further  disintegration. 

In  the  soils  in  the  neighborhood  of  the  Rhine  and 
Nile,  which  contain  much  potash,  and  where  crops 
can  be  obtained  in  close  succession  from  the  same 
field,  the  fallowing  of  the  land  is  superseded  by  the 
inundation ;  the  irrigation  of  meadows  effects  the 
same  purpose.  It  is  because  the  water  of  rivers  and 
streams  contains  oxygen  in  solution,  that  it  effiects 
the  most  complete  and  rapid  putrefaction  of  the  ex- 
crements contained  in  the  soil  which  it  pene-trates, 
and  in  which  it  is  continually  renewed.  If  it  was 
the  water  alone  which  produced  this  effect,  marshy 


CULTIVATION  OF  MEADOWS.  169 

meadows  should  be  most  fertile.  Hence  it  is  not 
sufficient  in  irrigating  meadows  to  convert  them  into 
marshes,  by  covering  for  several  months  their  sur- 
face with  water,  w^hich  is  not  renewed;  for  the 
advantage  of  irrigation  consists  principally  in  sup- 
plying oxygen  to  the  roots  of  plants.  The  quantity 
of  water  necessary  for  this  purpose  is  very  small,  so 
that  it  is  sufficient  to  cover  the  meadow  with  a  very 
thin  layer,  if  this  be  frequently  renewed. 

The  cultivation  of  meadows  forms  one  of  the  most 
important  branches  of  rural  economy.  It  contributes 
materially  to  the  prosperity  of  the  agriculturist  by 
increasing  his  stock  of  cattle,  and  consequently  by 
furnishing  him  with  manure,  which  may  be  applied 
to  the  augmentation  of  his  crops.  Indeed,  the  great 
progress  which  has  been  made  in  Germany  in  the 
improvement  of  cattle  is  mainly  attributable  to  the 
attention  which  is  devoted  in  that  country  to  the 
culture  of  meadows.  The  environs  ,of  Siegin,  in 
Nassau,  are  particulary  famed  in  this  respect,  and 
every  year  a  large  number  of  young  farmers  repair 
to  it,  for  the  purpose  of  studying  this  branch  of 
agriculture  in  situ.  In  that  district  the  culture  of 
grass  has  attained  such  great  perfection,  that  the 
produce  of  their  meadow-land  far  exceeds  that  ob- 
tained in  any  other  part  of  Germany.  This  is  effected 
simply  by  preparing  the  ground  in  such  a  manner  as 
to  enable  it  to  be  irrigated  both  in  spring  and  in 
autumn.  The  surface  of  the  soil  is  fitted  to  suit  the 
locality,  and  the  quantity  of  water  which  can  be 
commanded.  Thus  if  the  meadows  be  situated  upon 
a  declivity,  banks  of  from  one  to  two  feet  in  height 
are  raised  at  short  distances  from  each  other.  The 
water  is  admitted  by  small  channels  upon  the  most 
elevated  bank,  and  allowed  to  discharge  itself  over 
the  sides  in  such  a  manner  as  to  run  upon  the  bank 
situated  below.  The  grass  grown  upon  meadow^s 
irrigated  in  this  way  is  three  or  four  times  higher 
than  that  obtained  from  fields  which  are  covered  with, 
water  that  is  deprived  of  all  egress  and  renewal, 
fe  15 


170  ,  THE  ALTERNATION  OF  CROPS. 

It  follows  from  what  has  preceded,  that  the  ad- 
vantage of  the  alternation  of  crops  is  owing  to  two 
causes. 

A  fertile  soil  ought  to  afford  to  a  plant  all  the  in- 
organic bodies  indispensable  for  its  existence  in  suf- 
ficient quantity  and  in  such  condition  as  allow^s  their 
absorption. 

All  plants  require  alkalies,  which  are  contained  in 
some,  in  the  GraminecB  for  example,  in  the  form  of 
silicates ;  in  others,  in  that  of  tartrates,  citrates,, 
acetates,  or  oxalates. 

When  these  alkalies  are  in  combination  with  silicic 
acid,  the  ashes  obtained  by  the  incineration  of  the 
plant  contain  no  carbonic  acid ;  but  when  they  are 
united  with  organic  acids,  the  addition  of  a  mineral 
acid  to  their  ashes  causes  an  effervescence. 

A  third  species  of  plants  requires  phosphate  of 
lime,  another  phosphate  of  magnesia,  and  several  do 
not  thrive  without  carbonate  of  lime. 

Silicic  acid  *  is  the  first  solid  substance  taken  up 
by  plants ;  it  appears  to  be  the  material  from  which 

*  Silica,  or  siliceous  earth,  is  the  most  abundant  ingredient  in  the 
mineral  kingdom,  being  one  of  the  constituents  of  most  rocks,  and 
extensively  distributed  over  the  earth  in  the  form  of  sand,  quartz, 
carnelian,  flint,  &c.,  &c.  It  is  also  held  in  solution  by  the  water 
of  hot  springs,  as  in  the  Geysers  of  Iceland,  and  the  Azores,  from 
which  it  is  deposited,  forming  what  is  called  siliceous  sinter,  and  often 
incrusting  the  stems  of  plants  and  other  bodies.  The  vegetable  mat- 
ter in  some  instances  has  entirely  disappeared,  and  the  silica  having 
taken  its  place  we  have  silicified  or  petrified  wood,  &c.  See  Web- 
ster's Description  of  the  Island  of  St.  Michael^  p.  208.  From  siHca  a 
substance  is  obtained  which  is  considered  as  its  base  and  called  silicon 
and  silicium.  This  base,  combined  with  oxygen,  constitutes  silica, 
which  is  capable  of  combining  with  other  bases ;  from  this  and  other 
properties  it  is  called  silicic  acid.  By  combination  with  other  sub- 
stances, as  potash,  soda,  &c.,  silica  becomes  soluble  in  water.  These 
compounds  are  called  silicates.  A  white,  earthy  substance  is  found  be- 
neath peat  and  in  swampy  lands  and  ponds,  which  has  long  been  mis- 
taken for  calcareous  marl.  It  has  been  proved  to  consist  of  the  siliceous 
skeletons  of"  infusorial  vegetables,  if  they  may  be  so  called,  or  of  those 
equivocal  beings,  which  occupy  the  borders  of  the  two  kingdoms,  and 
render  it  difficult,  not  to  say  impossible,  to  draw  the  line  between 
them."  This  siliceous  deposite  has  been  found  under  nearly  every  peat 
bog  in  this  country  which  has  been  examined.  See  Professor  Bailey's 
paper  in  American  Journal  of  Science.  Vol.  XXXV.  p.  118,  and  Vol. 
XL.  p.  174. 


CAUSES  OF  ITS  BENEFICIAL  INFLUENCE.  171 

the  formation  of  the  wood  takes  its  origin,  actino- 
like  a  grain  of  sand  around  which  the  first  crystals 
form  in  a  solution  of  a  salt  which  is  in  the  act  of 
crystallizing.  Silicic  acid  appears  to  perform  the 
function  of  woody  fibre  in  the  Equisetacece  and  bam- 
boos,^ just  as  the  crystalline  salt,  oxalate  of  lime, 
does  in  many  of  the  lichens. 

When  we  grow  in  the  same  soil  for  several  years 
in  succession  different  plants,  the  first  of  which 
leaves  behind  that  which  the  second,  and  the  second 
that  which  the  third  may  require,  the  soil  will  be  a 
fruitful  one  for  all  the  three  kinds  of  produce.  If 
the  first  plant,  for  example,  be  wheat,  which  con- 
sumes the  greatest  part  of  the  silicate  of  potash  in  a 
soil,  whilst  the  plants  which  succeed  it  are  of  such 
a  kind  as  require  only  small  quantities  of  potash,  as 
is  the  case  with  Leguminosce,  turnips,  potatoes,  &c., 
the  wheat  may  be  again  sowed  with  advantage  after 
the  fourth  year;  for  during  the  interval  of  three 
years  the  soil  will,  by  the  action  of  the  atmosphere, 
be  rendered  capable  of  again  yielding  silicate  of  pot- 
ash in  sufficient  quantity  for  the  young  plants. 

The  same  precautions  must  be  observed  with  re- 
gard to  the  other  inorganic  constituents,  when  it  is 
desired  to  grow  different  plants  in  succession  on  the 
same  soil :  for  a  successive  growth  of  plants  which 
extract  the  same  components  parts,  must  gradually 
render  it  incapable  of  producing  them.  Each  of 
these  plants  during  its  growth  returns  to  the  soil  a 
certain  quantity  of  substances  containing  carbon, 
which  are  gradually  converted  into  humus,  and  are 
for  the  most  part  equivalent  to  as  much  carbon  as 
the  plants  had  formerly  extracted  from  the  soil  in  a 
state  of  carbonic  acid.  But  although  this  is  sufficient 
to  bring  many  plants  to  maturity,  it  is  not  enough 
to  furnish  their  different  organs  with  the  greatest 
possible  supply  of  nourishment.     Now  the  object  of 

*  Silica  is  found  in  the  joints  of  bamboos,  in  the  form  of  small  round 
globules,  which  have  received  the  name  of  Tabasheer,  and  are  dis- 
tinguished by  their  remarkable  optical  properties.  —  Ed. 


172  THE  ALTERNATION  OF  CROPS. 

agriculture  is  to  produce  either  articles  of  commerce, 
or  food  for  man  and  animals ;  but  a  maximum  of 
produce  in  plants  is  always  in  proportion  to  the 
quantity  of  nutriment  supplied  to  them  in  the  first 
stage  of  their  development. 

The  nutriment  of  young  plants  consists  of  car- 
bonic acid,  contained  in  the  soil  in  the  form  of 
humus,  and  of  nitrogen  in  the  form  of  ammonia, 
both  of  which  must  be  supplied  to  the  plants,  if  the 
desired  purpose  is  to  be  accomplished.  The  forma- 
tion of  ammonia  cannot  be  effected  on  cultivated 
land,  but  humus  may  be  artificially  produced ;  and 
this  must  be  considered  as  an  important  object  in 
the  alternation  of  crops,  and  as  the  second  reason 
of  its  peculiar  advantages. 

The  sowing  of  a  field  with  fallow  plants,  such  as 
clover,  rye,  buck-wheat,  &c.,  and  the  incorporation 
of  the  plants,  when  nearly  at  blossom,  with  the  soil, 
affect  this  supply  of  humus  in  so  far,  that  young 
plants  subsequently  growing  in  it  find,  at  a  certain 
period  of  their  growth,  a  maximum  of  nutriment, 
that  is,  matter  in  the  process  of  decay. 

The  same  end  is  obtained,  but  with  much  greater 
certainty,  when  the  field  is  planted  with  sainfoin  or 
lucern.*  These  plants  are  remarkable  on  account 
of  the  great  ramification  of  their  roots,  and  strong 
development  of  their  leaves,  and  for  requiring  only 
a  small  quantity  of  inorganic  matter.  Until  they 
reach  a  certain  period  of  their  growth,  they  retain 
all  the  carbonic  acid  and  ammonia  which  may  have 
been  conveyed  to  them  by  rain  and  the  air,  for  that 
which  is  not  absorbed  by  the  soil  is  appropriated  by 
the   leaves  ;    they  also  possess  an  extensive  four  or 

*  The  alternation  of  crops  with  sainfoin  and  lucern  is  now  univer- 
sally adopted  in  Bingen  and  its  vicinity,  as  well  as  in  the  Palatinate; 
the  fields  in  these  districts  receive  manure  only  once  every  nine  years. 
In  the  first  years  after  the  land  has  been  manured  turnips  are  sown 
upon  it,  in  the  next  following  years  barley,  with  sainfoin  or  lucern ;  in 
the  seventh  year  potatoes,  in  the  eighth  wheat,  in  the  ninth  barley; 
on  the  tenth  year  it  is  manured,  and  then  the  same  rotation  again  takes 
place.  — L. 


CAUSES  OF  ITS  BENEFICIAL  INFLUENCE.  173 

six-fold  surface,  capable  of  assimilating  these  bodies, 
and  of  preventing  the  volatilization  of  the  ammonia 
from  the  soil,  by  completely  covering  it  in. 

An  immediate  consequence  of  the  production  of 
the  green  principle  of  the  leaves,  and  of  their  re- 
maining component  parts,  as  well  as  those  of  the 
stem,  is  the  equally  abundant  excretion  of  organic 
matters  into  the  soil  from  the  roots. 

The  favorable  influence  which  this  exercises  on  the 
land,  by  furnishing  it  with  matter  capable  of  being 
converted  into  humus,  lasts  for  several  years,  but 
barren  spots  gradually  appear  after  the  lapse  of 
some  time.  Now  it  is  evident  that,  after  from  six 
to  seven  years,  the  ground  must  become  so  impreg- 
nated with  excrements,  that  every  fibre  of  the  root 
will  be  surrounded  with  them.  As  they  remain  for 
some  time  in  a  soluble  condition,  the  plants  must 
absorb  part  of  them  and  suffer  injurious  effects  in 
consequence,  because  they  are  not  capable  of  assim- 
ilation. When  such  a  field  is  observed  for  several 
years,  it  is  seen  that  the  barren  spots  are  again  cov- 
ered with  vegetation,  (the  same  plants  being  always 
supposed  to  be  grown,)  whilst  new  spots  become 
bare  and  apparently  unfruitful,  and  so  on  alternately. 
The  causes  which  produce  this  alternate  barrenness 
and  fertility  in  the  different  parts  of  the  land  are 
evident.  The  excrements  upon  the  barren  spots 
receiving  no  new  addition,  and  being  subjected  to 
the  influence  of  air  and  moisture,  they  pass  into 
putrefaction,  and  their  injurious  influence  ceases. 
The  plants  now  find  those  substances  which  formerly 
prevented  their  growth  removed,  and  in  their  place 
meet  with  humus,  that  is,  vegetable  matter  in  the  act 
of  decay. 

We  can  scarcely  suppose  a  better  means  of  pro- 
ducing humus  than  by  the  growth  of  plants,  the 
leaves  of  which  are  food  for  animals  ;  for  they  pre- 
pare the  soil  for  plants  of  every  other  kind,  but 
particularly  for  those  to  which,  as  to  rape  and  flax, 

15* 


174  OF  MANURE. 

the  presence  of  humus  is  the  most  essential  condi- 
tion of  growth. 

The  reasons  why  this  interchange  of  crops  is  so 
advantageous,  —  the  principles  which  regulate  this 
part  of  agriculture,  are,  therefore,  the  artificial  pro- 
duction of  humus,  and  the  cultivation  of  different 
kinds  of  plants  upon  the  same  field,  in  such  an  order 
of  succession,  that  each  shall  extract  only  certain 
components  of  the  soil,  whilst  it  leaves  behind  or 
restores  those  which  a  second  or  third  species  of 
plant  may  require  for  its  growth  and  perfect  devel- 
opment. 

Now,  although  the  quantity  of  humus  in  a  soil  may 
be  increased  to  a  certain  degree  by  an  artificial 
cultivation,  still,  in  spite  of  this,  there  cannot  be  the 
smallest  doubt  that  a  soil  must  gradually  lose  those 
of  its  constituents  which  are  removed  in  the  seeds, 
roots,  and  leaves  of  the  plants  raised  upon  it.  The 
fertility  of  a  soil  cannot  remain  unimpaired,  unless 
we  replace  in  it  all  those  substances  of  which  it  has 
been  thus  deprived. 

Now  this  is  effected  by  manure. 


CHAPTER   IX. 

OF  MANURE. 

When  it  is  considered  that  every  constituent  of 
the  body  of  man  and  animals  is  derived  from  plants, 
and  that  not  a  single  element  is  generated  by  the 
vital  principle,  it  is  evident  that  all  the  inorganic 
constituents  of  the  animal  organism  must  be  re- 
garded, in  some  respect  or  other,  as  manure.  During 
their  life,  the  inorganic  components  of  plants  which 
are  not  required  by  the  animal  system,  are  disen- 
gaged from  the  organism,  in  the  form  of  excrements. 
After  their  death,  their  nitrogen  and  carbon  pass 
into   the   atmosphere  as  ammonia  and  carbonic  acid, 


ANIMAL  MANURE.  175 

the  products  of  their  putrefaction,  and  at  last  noth- 
ing remains  except  the  phosphate  of  lime  and  other 
salts  in  their  bones.  Now  this  earthy  residue  of  the 
putrefaction  of  animals  must  be  considered,  in  a 
rational  system  of  agriculture,  as  a  powerful  manure 
for  plants,  because  that  which  has  been  abstracted 
from  a  soil  for  a  series  of  years  must  be  restored  to 
it,  if  the  land  is  to  be  kept  in  a  permanent  condition 
of  fertility. 


ANIMAL    MANURES. 

We  may  now  inquire  whether  the  excrements  of 
animals,  which  are  employed  as  manure,  are  all  of 
a  like  nature  and  power,  and  whether  they,  in  every 
case,  administer  to  the  necessities  of  a  plant  by  an 
identical  mode  of  action.  These  points  may  easily 
be  determined  by  ascertaining  the  composition  of 
the  animal  excrements,  because  we  shall  thus  learn 
what  substances  a  soil  really  receives  by  their  means. 
According  to  the  common  view,  the  action  of  solid 
animal  excrements  depends  on  the  decaying  organic 
matters  which  replace  the  humus,  and  on  the  pres- 
ence of  certain  compounds  of  nitrogen,  which  are 
supposed  to  be  assimilated  by  plants,  and  employed 
in  the  production  of  gluten  and  other  azotized  sub- 
stances. But  this  view  requires  further  confirmation 
with  respect  to  the  solid  excrements  of  animals,  for 
they  contain  so  small  a  proportion  of  nitrogen,  that 
they  cannot  possibly  by  means  of  it  exercise  any 
influence  upon  vegetation. 

We  may  form  a  tolerably  correct  idea  of  the  chem- 
ical nature  of  the  animal  excrement  without  further 
examination,  by  comparing  the  excrements  of  a  dog 
with  its  food.  When  a  door  is  fed  with  flesh  and 
bones,  both  of  which  consist  in  great  part  of  organic 
substances  containing  nitrogen,  a  moist  white  excre- 
ment is  produced  which  crumbles  gradually  to  a  dry 
powder  in  the  air.     This  excrement  consists  of  the 


176  OF  MANURE. 

phosphate  of  lime  of  the  bones,  and  contains  scarce- 
ly TOO  part  of  its  weight  of  foreign  organic  substan- 
ces. The  whole  process  of  nutrition  in  an  animal 
consists  in  the  progressive  extraction  of  all  the  ni- 
trogen from  the  food,  so  that  the  quantity  of  this 
element  found  in  the  excrements  must  always  be  less 
than  that  contained  in  the  nutriment.  The  analysis 
of  the  excrements  of  a  horse  by  Macaire  and  Marcet 
proves  this  fact  completely.  The  portion  of  excre- 
ments subjected  to  analysis  was  collected  whilst 
fresh,  and  dried  in  vacuo  over  sulphuric  acid ;  100 
parts  of  it  (corresponding  to  from  350  to  400  parts 
of  the  dung  before  being  dried)  contained  0*8  of 
nitrogen.  Now  every  one  who  has  had  experience 
in  this  kind  of  analysis  is  aware,  that  a  quantity  un- 
der one  per  cent,  cannot  be  determined  with  accura- 
cy. We  should,  therefore,  be  estimating  its  propor- 
tion at  a  maximum,  were  we  to  consider  it  as  equal 
to  one-half  per  cent.  It  is  certain,  however,  that 
these  excrements  are  not  entirely  free  from  nitrogen, 
for  they  .emit  ammonia  when  digested  with  caustic 
potash. 

The  excrements  of  a  cow,  on  combustion  with  ox- 
ide of  copper,  yielded  a  gas  which  contained  one 
vol.  of  nitrogen  gas,  and  26*30  vol.  of  carbonic  acid. 

100  parts  of  fresh  excrements  contained 

Nitrogen 0-506 

Carbon 6-204 

Hydrogen 0*824 

Oxygen 4-818 

Ashes 1-748 

Water    .        .        .        .        .        .      85-900 

100000 

Now,  according  to  the  analysis  of  Boussingault, 
which  merits  the  greatest  confidence,  hay  contains 
one  per  cent,  of  nitrogen ;  consequently  in  the  25  lbs. 
of  hay  which  a  cow  consumes  daily,  |  of  a  lb.  of  ni- 
trogen must  have  been  assimilated.  This  quantity 
of  nitrogen  entering  into  the  composition  of  muscu- 
lar fibre  would  yield  8*3  lbs.  of  flesh  in  its   natural 


ITS  ESSENTIAL  ELEMENTS.  177 

condition.*  The  daily  increase  in  size  of  a  cow  is, 
however,  much  less  than  this  quantity.  We  find  that 
the  nitrogen,  apparently  deficient,  is  actually  con- 
tained in  the  milk  and  urine  of  the  animal.  The 
urine  of  a  milch-cow  contains  less  nitrogen  than  that 
of  one  which  does  not  yield  milk;  and  as  long  as  a 
cow  yields  a  plentiful  supply  of  milk,  it  cannot  be 
fattened.  We  must  search  for  the  nitrogen  of  the 
food  assimilated,  not  in  the  solid,  but  in  the  liquid 
excrements.  The  influence  which  the  former  exer- 
cise on  the  growth  of  vegetables  does  not  depend 
upon  the  quantity  of  nitrogen  which  they  contain. 
For  if  this  were  the  case,  hay  should  possess  the 
same  influence ;  that  is,  from  20  to  25  lbs.  ought  to 
have  the  same  power  as  100  lbs.  of  fresh  cow-dung. 
But  this  is  quite  opposed  to  all  experience. 

Which  then  are  the  substances  in  the  excrements 
of  the  cow  and  horse  which  exert  an  influence  on 
vegetation? 

When  horse-dung  is  treated  with  water,  a  portion 
of  it  to  the  amount  of  3  or  3J  per  cent,  is  dissolved, 
and  the  water  is  colored  yellow.  The  solution  is 
found  to  contain  phosphate  of  magnesia,  and  salts 
of  soda,  besides  small  quantities  of  organic  matters.f 

*  100  lbs.  of  flesh  contain  on  an  average  15-86  of  muscular  fibre  :  18 
parts  of  nitrogen  are  contained  in  100  parts  of  the  latter.  —  L. 

The  flesh  of  animals  when  digested  in  repeated  portions  of  cold  wa- 
ter, affords  albumen,  saline  substances,  and  coloring  and  extractive 
matters.  When  the  part  that  is  no  longer  acted  on  by  cold  water  is  di- 
gested in  hot  water,  the  cellular  substance  is  removed  in  the  form  of 
gelatine^  and  fatty  matter  separates.  The  insoluble  residue  is  princi- 
pally jtirme. 

The  following  is  the  proportion  of  water,  albumen,  and  gelatine  in 
the  muscular  parts  of  several  animals  and  fishes. 


100  parts  of 

Albumen  or 

Total  of 

Muscle  of          Water. 

Fibrine. 

Gelatine. 

Nutritive  Matter. 

Beef,                74 

20 

6 

26 

Veal,                75 

19 

6 

25 

Mutton,           71 

22 

7 

29 

Pork,                76 

19 

5 

24 

Chicken,          73 

20 

7 

27 

Cod,                 79 

14 

7 

21 

Haddock,         82 

13 

5 

18 

See  Brande's 

Chemistry  J  4  th 

edit, 

p.  1184. 

t  Dr.  C.  T.  Jackson 

in  his  '*  Geolosn. 

cal  and  .^Agricultural 

'  Survey  of 

Rhode  Island^''  (page  205,)  gives  the  following  analysis 

of  horse-dung : 

178  OF  MANURE. 

The  portion  of  the  dung  undissolved  by  the  water 
yields  to  alcohol  a  resinous  substance  possessing  all 
the  characters  of  gall  which  has  undergone  some 
change;  while  the  residue  possesses  the  properties 
of  sawdust,  from  which  all  soluble  matter  has  been 
extracted  by  water,  and  burns  without  any  smell. 
100  parts  of  the  fresh  dung  of  a  horse  being  dried  at 
100^  C.  (212^  F.)  leave  from  25  to  30  or  31  parts  of 
solid  substances,  and  contained,  accordingly,  from 
69  to  76  parts  cf  water.  From  the  dried  excrements, 
we  obtain,  by  incineration,  variable  quantities  of  salts 
and  earthy  matters  according  to  the  nature  of  the 
food  which  has  been  taken  by  the  animal.  Macaire 
and  Marcet  found  27  per  cent,  in  the  dung  analyzed 
by  them;  I  obtained  only  10  per  cent,  from  that  of 
a  horse  fed  with  chopped  straw,  oats,  and  hay.  It 
results  then  that  with  from  3900  to  4400  lbs.  of  fresh 
horse-dung,  corresponding  to  110  lbs.  of  dry  dung, 
we  place  on  the  land  from  2737  to  3006  lbs.  of  wa- 
ter, and  from  804  to  992  lbs.  of  vegetable  matter  and 
altered  gall,  and  also  from  110  to  297  lbs.  of  salt 
and  other  inorganic  substances. 

The  latter  are  evidently  the  substances  to  which 
our  attention  should  be  directed,  for  they  are  the 
same  which  formed  the  component  parts  of  the  hay, 
straw,  and  oats  with  which  the  horse  was  fed.    Their 

—  500  grains,  dried  at  a  heat  a  little  above  that  of  boiling  water,  lost 
357  grains  of  water.  The  dry  mass  weighing  143  grains  was  burned, 
and  left  8  grains  of  ashes,  of  which  4-81)  grains  were  soluble  in  dilute 
nitric  acid,  and  320  insoluble.     The  ashes  being  analyzed,  gave 

Silica 3-2 

Phosphate  of  lime 0-4 

Carbonate  of  lime 1'5 

Phosphate  of  magnesia  and  soda     .        .        29 

80 
It  consists,  then,  of  the  following  ingredients  :  — 

Water 3570 

Vegetable  fibre  and  animal  matter  .      1350 

Silica 3-2 

Phosphate  of  lime  .        .         .        .  0-4 

Carbonate  of  lime 1'5 

Phosphate  of  magnesia  and  soda    ,        .  2*9 

5000 


ITS  ESSENTIAL  ELEMENTS.  179 

principal  constituents  are  the  phosphates  of  lime  and 
magnesia,  carbonate  of  lime  and  silicate  of  potash ; 
the  first  three  of  these  preponderated  in  the  corn, 
the  latter  in  hay. 

Thus  in  1102  lbs.  <jf  horse-dung,  we  present  to  a 
field  the  inorganic  substances  contained  in  6612  lbs. 
of  hay,  or  9146  lbs.  of  oats  (oats  containing  3*1  per 
cent,  ashes  according  to  De  Saussure).  This  is  suf- 
ficient to  supply  1|  crop  of  wheat  with  potash  and 
phosphates. 

The  excrements  of  cows,*  black  cattle,  and  sheep, 
contain  phosphate  of  lime,  common  salt,  and  silicate 
of  lime,  the  weight  of  which  varies  from  9  to  28  per 
cent.,  according  to  the  fodder  which  the  animal  re- 
ceives ;  the  fresh  excrements  of  the  cow  contain  from 
86  to  90  per  cent,  of  water. 

Human  faeces  have  been  subjected  to  an  exact 
analysis  by  Berzelius.  When  fresh  they  contain,  be- 
sides I  of  their  weight  of  water,  nitrogen  in  very 
variable  quantity,  namely,  in  the  minimum  IJ,  in  the 
maximum  5  per  cent.  In  all  cases,  however,  they 
were  richer  in  this  element  than  the  excrements  of 
other  animals.  Berzelius  obtained  by  the  incinera- 
tion of  100  parts  of  dried  excrements,  15  parts  of 
ashes,  which  were  principally  composed  of  the  phos- 
phates of  lime  and  magnesia. 

The  following  quantitative  organic  analysis  has 
recently  been  executed  for  the  purpose  of  ascertain- 

*  It  has  been  formerly  stated  (page  120),  that  all  the  potash  contained 
in  the  food  of  a  cow  is  again  discharged  in  its  excrements.  The  same 
also  takes  place  with  the  other  inorganic  constituents  of  food,  either 
when  they  are  not  adapted  for  assimilation,  or  when  present  in  supera- 
bundant quantities.  The  value  of  manure  may  thus  be  artificially  in- 
creased. We  lately  saw,  for  example,  some  cow-dung,  sent  by  a  farm- 
er, who  wished  to  ascertain  the  cause  of  its  increased  value.  He  had 
formerly  employed  this  manure  for  his  land,  but  with  so  little  advan- 
tage that  he  found  it  more  profitable  to  dry  it,  and  use  it  as  fuel.  On 
inquiry,  it  was  found,  that  his  cows  had  been  fed  upon  oil-cakes.  This 
species  of  food  is  particularly  rich  in  phosphates.  More  of  these  salts 
being  present  than  were  requisite  for  the  purpose  of  assimilation,  they 
were  removed  from  the  system  in  the  form  of  excrementitious  matter, 
and  in  a  condition  adapted  for  the  uses  of  plants.  The  fact  that  partic- 
ular kinds  of  food  enrich  or  impoverish  the  manure  obtained  from  the 
cattle  fed  upon  them,  has  repeatedly  been  observed.  —  £d. 


180  OF  MANURE. 

ing  the  proportion  of  carbon,  nitrogen,  and  inorganic 
matter  contained  in  faeces,  in  comparison  with  the 
food  taken.*    (Playfair.) 

Carbon 45-24 

Hydrogen        ....#...  6-88 

Nitrogen  (average) 4- 00 

Oxygen 3030 

Ashes 13-58 

The  inorganic  matter  contained  in  the  excrements 
analyzed  is  nearly  two  per  cent,  less  than  that  found 
by  Berzelius ;  but  the  proportion  always  varies,  ac- 
cording to  the  nature  of  the  food. 

It  is  quite  certain,  that  the  vegetable  constituents 
of  the  excrements  with  which  we  manure  our  fields 
cannot  be  entirely  without  influence  upon  the  growth 
of  the  crops  on  them,  for  they  will  decay,  and  thus 
furnish  carbonic  acid  to  the  young  plants.  But  it 
cannot  be  imagined  that  their  influence  is  very  great, 
when  it  is  considered  that  a  good  soil  is  manured 
only  once  every  six  or  seven  years,  or  once  every 
eleven  or  twelve  years,^when  sainfoin  or  lucern  has 
been  raised  on  it,  that  the  quantity  of  carbon  thus 
given  to  the  land  corresponds  to  only  5*8  per  cent, 
of  what  is  removed  in  the  form  of  herbs,  straw,  and 
grain ;  and  further  that  the  rain-water  received  by  a 
soil  contains  much  more  carbon  in  the  form  of  car- 
bonic acid  than  these  vegetable  constituents  of  the 
manure. 

The  peculiar  action  then,  of  the  solid  excrements 
is  limited  to  their  inorganic  constituents,  which  thus 
restore  to  a  soil  that  which  is  removed  in  the  form 
of  corn,  roots,  or  grain.  When  we  manure  land  with 
the  dung  of  the  cow  or  sheep,  we  supply  it  with 
silicate  of  potash  and  some  salts  of  phosphoric  acid. 
In  human  fseces  we  give  it  the  phosphates  of  lime 
and  magnesia;  and  in  those  of  the  horse,  phosphate 

*  The  details  of  the  analysis  are  as  follows:  —  2-356  grammes  left 
0320  gramme  ashes  after  incineration  ;  these  consisted  of  the  phosphate 
of  lime  and  magnesia.  0352  gramme  yielded,  on  combustion  with 
oxide  of  copper7o576  gram,  carbonic  acid,  and  0-218  gram,  water. 
(L.  P.) 


ITS  ESSENTIAL  ELEMENTS-  18 1 

of  magnesia,  and  silicate  of  potash.  In  the  straw 
which  has  served  as  litter,  we  add  a  further  quantity 
of  silicate  of  potash  and  phosphates ;  which,  if  the 
straw  be  putrefied,  are  in  exactly  the  same  condition 
in  which  they  were  before  being  assimilated. 

It  is  evident,  therefore,  that  the  soil  of  a  field  will 
alter  but  little,  if  we  collect  and  distribute  the  dung 
carefully  ;  a  certain  portion  of  the  phosphates,  how- 
ever, must  be  lost  every  year,  being  removed  from  the 
land  with  the  corn  and  cattle,  and  this  portion  will 
accumulate  in  the  neighborhood  of  large  towns.  The 
loss  thus  suffered  must  be  compensated  for  in  a  w^ell- 
managed  farm,  and  this  is  partly  done  by  allowing 
the  fields  to  lie  in  grass.  In  Germany,  it  is  con- 
sidered that  for  every  100  acres  of  corn  land,  there 
must,  in  order  to  effect  a  profitable  cultivation,  be 
20  acres  of  pasture-land,  which  produce  annually,  on 
an  average^  551  lbs.  of  hay.  Now  assuming  that 
the  ashes  of  the  excrements  of  the  animals  fed  with 
this  hay  amount  to  6*82  per  cent.,  then  376  lbs.  of 
the  silicate  of  lime  and  phosphates  of  magnesia  and 
lime  must  be  yielded  by  these  excrements,  and  will 
in  a  certain  measure  compensate  for  the  loss  whichi 
the  corn-land  had  sustained. 

The  absolute  loss  in  the  salts  of  phosphoric  acid,, 
which  are  not  again  replaced,  is  spread  over  so  great 
an  extent  of  surface,  that  it  scarcely  deserves  to  be 
taken  account  of.  But  the  loss  of  phosphates  is 
again  replaced  in  the  pastures  by  the  ashes  of  the 
wood  used  in  our  houses  for  fuel. 

We.  could  keep  our  fields  in  a  constant  state  of 
fertility  by  replacing  every  year  as  much  as  we  re- 
move from  them  in  the  form  of  produce ;  but  an  in- 
crease of  fertility,  and  consequent  increase  of  crop 
can  only  be  obtained  when  we  add  more  to  them 
than  we  take  away.  It  will  be  found,  that  of  two 
fields  placed  under  conditions  otherwise  similar,  the 
one  will  be  most  fruitful  upon  which  the  plants  are 
enabled  to  appropriate  more  easily  and  in  greater 
16 


182  OF  MANURE. 

abundance    those    contents    of   the    soil    which    are 
essential  to  their  growth  and  development. 

From  the  foregoing  remarks  it  will  readily  be  in- 
ferred, that  for  animal  excrements,  other  subtances 
containing  their  essential  constituents  may  be  sub- 
stituted. In  Flanders,  the  yearly  loss  of  the  necessary 
matters  in  the  soil  is  completely  restored  by  covering 
the  fields  with  ashes  of  wood  or  bones,  which  may 
or  may  not  have  been  lixiviated  *  and  of  which  the 
greatest  part  consists  of  the  phosphates  of  lime  and 
magnesia.  The  great  importance  of  manuring  with 
ashes  has  been  long  recognised  by  agriculturists  as 
the  result  of  experience.  So  great  a  value,  indeed, 
is  attached  to  this  material  in  the  vicinity  of  Mar- 
burg and  in  the  Wetterau,f  that  it  is  transported  as 
a  manure  from  the  distance  of  18  or  24  miles.  J  Its 
use  will  be  at  once  perceived,  when  it  is  considered 
that  the  ashes,  after  having  been  washed  with  water, 
contain  silicate  of  potash  exactly  in  the  same  pro- 
portion as  in  straw  (10  Si  0  3  -(-  K  0.),  and  that 
their  only  other  constituents  are  salts  of  phosphoric 
acid. 

But  ashes  obtained  from  various  kinds  of  trees  are 
of  very  unequal  value  for  this  purpose;  those  from 
oak-wood  are  the  least,  and  those  from  beech  the 
most  serviceable.  The  ashes  of  oak-wood  contain 
only  traces  of  phosphates,  those  of  beech  the  fifth 
part  of  their  weight,  and  those  of  the  pine  and  fir 
from  9  to  15  per  cent.  The  ashes  of  pines  from 
Norway  contain  an  exceedingly  small  quantity  of 
phosphates,  namely,  only  1*8  per  cent,  of  phosphoric 
acid.     (Berthier.)  § 

*  Lixiviation  signifies  the  removal  by  water  of  the  soluble  alkaline  or 
saline  matters  in  any  earthy  mixture ;  as  from  that  of  lime  and  potash, 
or  from  ashes  to  obtain  a  ley. 

t  Two  well  known  agricultural  districts;  the  first  in  Hesse-Cassel, 
the  second  in  Hesse-Darmstadt.  —  Trans. 

X  Ashes  are  used  with  great  advantage  on  the  light  siliceous  soil  of 
Long  Island,  Connecticut,  and  various  other  places  in  the  United 
States. 

^  "  The  existence  of  phosphate  of  lime  in  the  forest  soils  of  the  United 
States,  is  proved  not  only  by  its  existence  in  the  pollen  of  the  pinus 


BONE  MANURE.  183 

With  every  110  lbs.  of  the  lixiviated  ashes  of  the 
beech  which  we  spread  over  a  soil,  we  furnish  as 
much  phosphates  as  507  lbs.  of  fresh  human  excre- 
ments could  yield.  Again,  according  to  the  analysis 
of  De  Saussure,  100  parts  of  the  ashes  of  the  grain 
of  wheat  contain  32  parts  of  soluble,  and  44-5  of 
insoluble  phosphates,  in  all  76-5  parts.  Now  the 
ashes  of  wheat  straw  contain  11*5  per  cent,  of  the 
same  salts;  hence  with  every  110  lbs.  of  the  ashes 
of  the  beech,  we  supply  a  field  with  phosphoric  acid 
sufficient  for  the  production  of  4210  lbs.  of  straw 
(its  ashes  being  calculated  at  4*3  per  cent,  De 
Saussure),  or  for  16-20000  lbs.  of  corn,  the  ashes  of 
which  amount,  according  to  De  Saussure,  to  1*3  per 
cent. 

Bone  manure  possesses  a  still  greater  importance 
in  this  respect.  The  primary  sources  from  which 
the  bones  of  animals  are  derived  are,  the  hay,  straw, 
or  other  substances  which  they  take  as  food.  Now 
if  we  admit  that  bones  contain  55  per  cent,  of  the 
phosphates  of  lime  and  magnesia  (Berzelius),  and 
that  hay  contains  as  much  of  them  as  wheat  strait, 
it  will  follow  that  8*8 lbs.  of  bones  contain  as  much 
phosphate  of  lime  as  1102  lbs.  of  hay  or  wheat- 
straw,  and  2-2  lbs.  of  it  as  much  as  1102  lbs.  of  the 
grain  of  wheat  or  oats.  These  numbers  express 
pretty  nearly  the  quantity  of  phosphates  which  a 
soil  yields  annually  on  the  growth  of  hay  and  corn. 
Now  the  manure  of  an  acre  of  land  with  44  lbs.  of 
bone  dust  is  sufficient  to  supply  three  crops  of  wheat, 

abies  (which  is  composed  of  3  per  cent,  phosphate  of  lime  and  potash), 
but  by  its  actual  detection  in  the  ashes  of  pines  and  other  trees.  —  10(» 
parts  of  the  ashes  of  wood  ofpinus  abies  give  3  per  cent,  phosphate  of 
iron;  100  parts  of  the  ashes  of  the  coal  of  pinus  sylvestris  give  1  72 
phosphate  of  lime,  0*25  phosphate  of  iron ;  100  parts  of  ashes  of  oak 
coal  give  7-1  phosphate  of  lime,  3-7  phosphate  of  iron  ;  100  parts  of  the 
ashes  of  bass  wood  give  5  4  phosphate  of  lime,  3*2  phosphate  of  iron  ; 
100  parts  of  the  ashes  of  birch  wood  give  7*3  phosphate  of  lime,  1-25 
phosphate  of  iron ;  100  parts  of  the  ashes  of  oak  wood  give  1-8  phos- 
phate of  lime  ;  100  parts  of  the  ashes  of  alder  coal  give  345  phosphate 
of  lime,  9  phosphate  of  iron.  These  are  the  calculated  results  from 
Berthier's  analyses."  —  Dr.  S.  L.  Dana,  in  Report  on  a  Reexamination 
of  the  Economical  Geology  of  Massachusetts. 


184  OF  MANURR 

clover,  potatoes,  turnips,  &c.,  with  phosphates.  But 
the  form  in  which  they  are  restored  to  a  soil  does 
not  appear  to  be  a  matter  of  indifference.  For  the 
more  finely  the  bones  are  reduced  to  powder,  and 
the  more  intimately  they  are  mixed  with  the  soil, 
the  more  easily  are  they  assimilated.  The  most  easy 
and  practical  mode  of  effecting  their  division  is  to 
pour  over  the  bones,  in  a  state  of  fine  powder,  half 
of  their  weight  of  sulphuric  acid  diluted  with  three 
or  four  parts  of  water,  and  after  they  have  been 
digested  for  some  time,  to  add  one  hundred  parts 
of  water,  and  sprinkle  this  mixture  over  the  field 
before  the  plough.  In  a  few  seconds,  the  free  acids 
unite  with  the  bases  contained  in  the  earth,  and  a 
neutral  salt  is  formed  in  a  very  fine  state  of  division. 
Experiments  instituted  on  a  soil  formed  from  grau- 
wacke,  for  the  purpose  of  ascertaining  the  action  of 
manure  thus  prepared,  have  distinctly  shown  that 
neither  corn,  nor  kitchen-garden  plants,  suffer  in- 
jurious effects  in  consequence,  but  that  on  the  con- 
trary they  thrive  with  much  more  vigor. 

It  has  also  been  found,  that  bones  act  more  speed- 
ily and  efficaciously  after  being  boiled.  This  is 
probably  owing  to  the  removal  of  fatty  matter,  the 
presence  of  which  impedes  the  putrefaction  of  the 
gelatin  contained  in  them. 

In  the  manufactories  of  glue,  many  hundred  tons 
of  a  solution  of  phosphates  in  muriatic  acid  are 
yearly  thrown  away  as  being  useless.  It  would  be 
important  to  examine  whether  this  solution  might 
not  be  substituted  for  the  bones.  The  free  acid 
would  combine  with  the  alkalies  in  the  soil,  espec- 
ially w^ith  the  lime,  and  a  soluble  salt  would  thus  be 
produced,  which  is  known  to  possess  a  favorable 
action  upon  the  growth  of  plants.  This  salt,  muriate 
of  lime  (or  chloride  of  calcium),  is  one  of  those 
compounds  which  attracts  water  from  the  atmosphere 
with  great  avidity,  and  in  dry  lands  might  advan- 
tageously supply  the  place  of  gypsum  in  decompos- 
ing  carbonate   of   ammonia,   with   the  formation  of 


EXPLANATION  OF  ITS  ACTION.        '  185 

sal-ammoniac  and  carbonate  of  lime.  A  solution  of 
bones  in  muriatic  acid  placed  on  land  in  autumn  or 
in  winter  would,  therefore,  not  only  restore  a  neces- 
sary constituent  of  the  soil,  and  attract  moisture  to 
it,  but  would  also  give  it  the  power  to  retain  all  the 
ammonia  which  fell  upon  it  dissolved  in  the  rain 
during  the  period  of  six  months.* 

The  ashes  of  brown  coal  f  and  peat  often  contain 
silicate  of  potash,{  so  that  it  is  evident,  that   these 

*  Immense  quantities  of  bran  are  used  in  all  printworks,  for  the 
purpose  of  clearing  printed  goods.  After  having  served  this  purpose, 
it  is  thrown  away.  But  the  insoluble  part  of  bran  contains  much 
phosphates  of  magnesia  and  soda;  it  would  therefore  be  useful  to  pre- 
serve it  as  a  manure.  This  has  been  done  for  some  years  in  a  farm 
with  which  I  am  connected,  and  its  value  as  a  manure  has  been  found 
so  great  that  it  is  much  preferred  to  cow-dung.  In  some  works  this 
waste  bran  is  heaped  up  into  little  hillocks,  which  might  be  disposed 
of  as  a  manure,  instead  of  being  an  annoyance  on  account  of  the  space 
which  it  occupies.  —  Ed. 

t  Brown  coal.  Braunkohle,  Lignite  has  the  structure  and  appearance 
of  carbonized  wood.  It  occurs  abundantly  in  Germany  ;  in  Hessia  it 
forms  beds  20  to  40  feet  thick,  and  several  square  miles  in  extent. 
Fibrous  and  compact  varieties  occur  near  Bovey  Tracey  in  England, 
where  it  is  called  Bovey  coal.  Small  quantities  are  found  at  Gay  Head, 
Massachusetts. 

t  The  following  is  the  result  of  an  analysis  by  Dr.  C.  T.  Jackson, 
of  peat  from  Lexington,  Massachusetts.  100  grains,  dried  at  300°  F. 
weighed  74  grains,  loss  26  grains,  water.  Burned  in  a  platina  crucible 
it  left  50  ashes.     The  ashes  yielded 

Silex, .        10 

Alumina,  iron,  and  manganese,  .        .        .  0*6' 

Phosphate  of  lime,         .         .         .         ...         .        3*0 

Potash,  traces.  — ■ 

4-6 
Peat  from  Watertown,  Massachusetts,  yielded  4-5  grains  of  ashes, 
which  gave  by  analysis 

Silex,  T-^S 

Alumina,  oxide  of  iron,  and  manganese,           .        .     15 
Phosphate  of  lime, 1'7 

4-5 

The  vegetable  matter  amounted  to  955  per  cent.,  consisting  of  veg- 
etable fibre,  and  apocrenic  and  crenic  acids,  in  part  combined  with  the 
bases  obtained  from  its  ashes.     See  Report  on  Rhode  Island,  p.  233. 

Swamp  muck  contains  the  same  ingredients  as  peat,  but  the  vegetable 
matters  are  more  finely  divided,  more  soluble,  and  there  is  generally  a 
larger  proportion  of  earthy  matters.  It  is  formed  of  the  fine  particles 
of  humus,  washed  out  from  the  upland  soils,  and  of  the  dead  and 
decomposed  leaves  and  roots  of  swamp  plants. 

The  pulpy  matter  of  both  peat  and  swamp  muck  consists  chiefly  of 
the  apocrenic  acid,  in  part  combined  with  the  earthy  bases,  and  me- 
tallic oxides.     The  crenic  acid  is  frequently  united  with  lime  and  man- 

16* 


186  OF  MANURE. 

might  completely  replace  one  of  the  principal  con- 
stituents of  the  dung  of  the  cow  and  horse,  and 
they  contain  also  some  phosphates.  Indeed,  they 
are  much  esteemed  in  the  Wetterau  as  manure  for 
meadows  and  moist  land. 

It  is  of  much  importance  to  the  agriculturist,  that 
he  should  not  deceive  himself  respecting  the  causes 
which  give  the  peculiar  action  to  the  substances  just 
mentioned.  It  is  known  that  they  possess  a  very 
favorable  influence  on  vegetation  ;  and  it  is  likewise 
certain  that  the  cause  of  this  is  their  containing  a 
body,-  which,  independently  of  the  influence  which 
it  exerts  by  virtue  of  its  form,  porosity,  and  capabil- 
ity of  attracting  and  retaining  moisture,  also  assists 
in  maintaining  the  vital  processes  in  plants.  If  it 
be  treated  as  an  unfathomable  mystery,  the  nature 
of  this  aid  will  never  be  known. 

In  medicine,  for  many  centuries,  the  mode  of 
action  of  all  remedies  was  supposed  to  be  concealed 
by  the  mystic  veil  of  Isis,  but  now  these  secrets 
have  been  explained  in  a  very  simple  manner.  An 
unpoetical  hand  has  pointed  out  the  cause  of  the 
wonderful  and  apparently  inexplicable  healing  vir- 
tues of  the  springs  in  Savoy,  by  which  the  inhabi- 
tants cured  their  goitre ;  it  was  shown  that  they 
contain  small  quantities  of  iodine.  In  burnt  sponges 
used  for  the  same  purpose,  the  same  element  was 
also  detected.  The  extraordinary  eflicacy  of  Peru- 
vian bark  was  found  to  depend  on  a  small  quantity 
of  a  crystalline  body  existing  in  it,  viz.  quinine;  and 
the  causes  of  the  various  effects  of  opium  were 
detected  in  as  many  different  ingredients  of  that 
drug. 

Calico-printers  used  for  a  long  time  the  solid 
excrements  of  the  cow,  in  order  to  brighten  and 
fasten    colors   on   cotton   goods ;    this   material   ap- 

ganese ;  iron  and  magnesia  occur  in  several  of  the  peats  analyzed. 
Phosphoric  acid  also  exists  in  them,  both  in  its  free  state,  and  in  com- 
bination with  lime  and  magnesia.  In  some  peats  Dr.  J.  found  traces 
of  oxalic  acid  and  oxalates.  Ibid.f  210.  See  Appendix,  for  Peat 
compost. 


EXPLANATION  OF  ITS  ACTION.  187 

peared  quite  indispensable,  and  its  action  was  as- 
cribed to  a  latent  principle  which  it  had  obtained 
from  the  living  organism.  But  since  its  action  was 
known  to  depend  on  the  phosphates  contained  in  it, 
it  has  been  completely  replaced  by  a  mixture  of 
salts,  in  which  the  principal  constituents  are  the 
phosphates  of  soda  and  lime.* 

Now  all  such  actions  depend  on  a  definite  cause,  by 
ascertaining  which  we  place  the  actions  themselves 
at  our  command. 

It  must  be  admitted  as  a  principle  of  agriculture, 
that  those  substances  which  have  been  removed  from 
a  soil  must  be  completely  restored  to  it,  and  whether 
this  restoration  be  effected  by  means  of  excrements, 
ashes,  or  bones,  is  in  a  great  measure  a  matter  of 
indifference.  A  time  will  come  when  fields  will  be 
manured  with  a  solution  of  glass  f  (silicate  of  pot- 
ash), with  the  ashes  of  burnt  straw,  and  with  salts 
of  phosphoric  acid,  prepared  in  chemical  manufac- 
tories, exactly  as  at  present  medicines  are  given  for 
fever  and  goitre. 

There  are  some  plants  which  require  humus,  and 
do  not  restore  it  to  the  soil  by  their  excrements ; 
whilst  others  can  do  without  it  altogether,  and  add 
humus  to  a  soil  which  contains  it  in  small  quantity. 
Hence  a  rational  system  of  agriculture  would  employ 
all  the  humus  at  command  for  the  supply  of  the 
former,  and  not  expend  any  of  it  for  the  latter;  and 
would  in  fact  make  use  of  them  for  supplying  the 
others  with  humus. 

We  have  now  considered  all  that  is  requisite  in  a 
soil,  in  order  to  furnish  its  plants  with  the  materials 
necessary  for  the  formation  of  the  woody  fibre,  the 

*  This  mixture  of  salts  is  sold  to  calico-printers  in  large  quantities 
under. the  name  of  '« dung  substitute."  It  would  be  well  worth  experi- 
ment to  try  its  effects  as  a  manure  upon  land.  Its  cost  is  3d.  or  4d.  per 
pound,  and  is  not,  therefore,  dearer  than  nitrate  of  soda,  which  is  now 
so  extensively  used.  —  Ed. 

t  When  glass  contains  a  very  large  proportion  of  potash,  it  is  soluble 
in  boiling  water ;  and  by  combination  with  other  substances,  silica 
becomes  soluble  in  water.  According  to  Dr.  Jackson,  crenic  acid 
enables  water  to  take  it  up. 


188  '      OF  MANURE. 

grain,  the  roots,  and  the  stem,  and  now  proceed  to 
the  consideration  of  the  most  important  object  of 
agriculture,  viz.  the  production  of  nitrogen  in  a  form 
capable  of  assimilation,  —  the  production,  therefore, 
of  substances  containing  this  element.  The  leaves, 
which  nourish  the  woody  matter,  the  roots,  from 
which  the  leaves  are  formed,  and  which  prepare  the 
substances  for  entering  into  the  composition  of  the 
fruit,  and,  in  short,  every  part  of  the  organism  of  a 
plant,  contain  azotized  matter  in  very  varying  pro- 
portions, but  the  seeds  and  roots  are  always  partic- 
ularly rich  in  them. 

Let  us  now  examine  in  what  manner  the  greatest 
possible  production  of  substances  containing  nitro- 
gen can  be  effected.  Nature,  by  means  of  the  atmo- 
sphere, furnishes  nitrogen  to  a  plant  in  quantity  suffi- 
cient for  its  normal  growth.  Now  its  growth  must 
be  considered  as  normal,  when  it  produces  a  single 
seed  capable  of  reproducing  the  same  plant  in  the 
following  year.  Such  a  normal  condition  would  suf- 
fice for  the  existence  of  plants,  and  prevent  their 
extinction,  but  they  do  not  exist  for  themselves 
alone ;  the  greater  number  of  animals  depend  on  the 
vegetable  world  for  food,  and  by  a  wise  adjustment 
of  nature,  plants  have  the  remarkable  power  of  con- 
verting, to  a  certain  degree,  all  the  nitrogen  offered 
to  them  into  nutriment  for  animals. 

We  may  furnish  a  plant  with  carbonic  acid,  and  all 
the  materials  which  it  may  require ;  we  may  supply 
it  with  humus  in  the  most  abundant  quantity ;  but  it 
will  not  attain  complete  development  unless  nitrogen 
is  also  afforded  to  it ;  a  herb  will  be  formed,  but  no 
grain ;  even  sugar  and  starch  may  be  produced  but 
no  gluten. 

But  when  we  give  a  plant  nitrogen  in  considera- 
ble quantity,  we  enable  it  to  attract  with  greater  en- 
ergy from  the  atmosphere  the  carbon  which  is  neces- 
sary for  its  nutrition,  when  that  in  the  soil  is  not 
sufficient ;  we  afford  to  it  a  means  of  fixing  the  car- 
bon of  the  atmosphere  in  its  organism. 


OF  URINE.  189 

We  cannot  ascribe  much  of  the  power  of  the  ex- 
crements of  black  cattle,  sheep,  and  horses,  to  the 
nitrogen  which  they  contain,  for  its  quantity  is  too 
minute.  But  that  contained  in  the  faeces  of  man  is 
proportionably  much  greater,  although  by  no  means 
constant.  In  the  faeces  of  the  inhabitants  of  towns, 
for  example,  who  feed  on  animal  matter,  there  is 
much  more  of  this  constituent  than  in  those  of  peas- 
ants, or  of  such  people  as  reside  in  the  country. 
The  faeces  of  those  who  live  principally  on  bread  and 
potatoes  are  similar  in  composition  and  properties  to 
those  of  animals. 

All  excrements  have  in  this  respect  a  very  varia- 
ble and  relative  value.  T-hus  those  of  black  cattle 
and  horses  are  of  great  use  on  soils  consisting  of 
lime  and  sand,  which  contain  no  silicate  of  potash 
and  phosphates ;  whilst  their  value  is  much  less  when 
applied  to  soils  formed  of  argillaceous  earth,  basalt, 
granite,  porphyry,  clinkstone,  and  even  mountain- 
limestone,  because  all  these  contain  potash  in  con- 
siderable quantity.  In  such  soils  human  excrements 
are  extremely  beneficial,  and  increase  their  fertility 
in  a  remarkable  degree ;  they  are,  of  course,  as  ad- 
vantageous for  other  soils  also;  but  for  the  manure 
of  those  first  mentioned,  the  excrements  of  other 
animals  are  quite  indispensable. 


OF    URINE. 


We  possess  only  one  other  natural  source  of  ma- 
nure which  acts  by  its  nitrogen,  besides  the  faeces 
of  animals,  —  namely,  the  urine  of  man  and  animals. 

Urine  is  employed  as  a  manure  either  in  the  liquid 
state,  or  with  the  faeces  which  are  impregnated  with 
it.  It  is  the  urine  contained  in  them  which  gives  to 
the  solid  faeces  the  property  of  emitting  ammonia, — 
a  property  v/hich  they  themselves  possess  only  in  a 
very  slight  degree. 

When  we  examine  what  substances  we  add  to  a 


190  OF  MANURE. 

soil  by  supplying  it  with  urine,  we  find  that  this 
liquid  contains  in  solution  ammoniacal  salts,  uric 
acid  (a  substance  containing  a  large  quantity  of  ni- 
trogen), and  salts  of  phosphoric  acid. 

According  to  Berzelius  1000  parts  of  human  urine 
contain :  — 

Urea .        .        .  3010 

Free  Lactic  acid,*  Lactate  of  Ammonia,  and  animal 

matter  not  separable  from  them          .        .        .  17.14 

Uric  acid l-OO 

Mucus  of  the  bladder 0  32 

Sulphate  of  Potash 371 

Sulphate  of  Soda 3-16 

Phosphate  of  Soda 2  94 

Phosphate  of  Ammonia 1'65 

Chloride  of  Sodium 4*45 

Muriate  of  Ammonia 1-50 

Phosphates  of  Magnesia  and  Lime      ...  J-OO 

Siliceous  earth 0-03 

Water 93300 

1000-00 

If  we  subtract  from  tli^  above  the  urea,  lactate  of 
ammonia,  free  lactic  acid,  uric  acid,  the  phosphate 
and  muriate  of  ammonia;  1  per  cent,  of  solid  matter 
remains,  consisting  of  inorganic  salts,  which  must 
possess  the  same  action  when  brought  on  a  field, 
whether  they  are  dissolved  in  water  or  in  urine. 
Hence  the  powerful  influence  of  urine  must  depend 
upon  its  other  ingredients,  namely,  the  urea  and  am- 
moniacal salts.  The  urea  in  human  urine  exists 
partly  as  lactate  of  urea,  and  partl}^  in  a  free  state. 
(Henry.)  Now  when  urine  is  allowed  to  putrefy 
spontaneously,  that  is,  to  pass  into  that  state  in 
which  it  is  used  as  manure,  all  the  urea  in  combina- 
tion with  lactic  acid  is  converted  into  lactate  of  am- 
monia, and  that  which  was  free,  into  volatile  carbon- 
ate of  ammonia. 

In  dung-reservoirs  well  constructed  and  protected 
from  evaporation,  this  carbonate  of  ammonia  is  re- 
tained in  the  state  of  solution,  and  when  the  putre- 

*  Lactic  acid  has  been  found  in  most  animal  fluids  and  in  several 
plants.  It  was  first  obtained  from  sour  milk,  heiice  its  name  from  the 
Latin  lac  J  milk. 


FIXATION  OF  AMMONIA.  191 

fied  urine  is  spread  over  the  land,  a  part  of  the  am- 
monia will  escape  with  the  water  which  evaporates, 
but  another  portion  will  be  absorbed  by  the  soil,  if 
it  contains  either  alumina  or  iron ;  but  in  general 
only  the  muriate,  phosphate,  and  lactate  of  ammonia 
remain  in  the  ground.  It  is  these  alone,  therefore, 
^  which  enable  the  soil  to  exercise  a  direct  influence 
on  plants  during  the  progress  of  their  growth,  and 
not  a  particle  of  them  escapes  being  absorbed  by 
the  roots. 

On  account  of  the  formation  of  this  carbonate  of 
ammonia  the  urine  becomes  alkaline,  although  it  is 
acid  in  its  natural  state.  When  it  is  lost  by  being 
volatilized  in  the  air,  which  happens  in  most  cases, 
the  loss  suffered  is  nearly  equal  to  one  half  of  the 
weight  of  the  urine  employed,  so  that  if  we  fix  it, 
that  is,  if  we  deprive  it  of  its  volatility,  we  increase 
its  action  twofold.  The  existence  of  carbonate  of 
ammonia  in  putrefied  urine  long  since  suggested  the 
manufacture  of  sal-ammoniac  from  this  material. 
When  the  latter  salt  possessed  a  high  price,  this 
manufacture  was  even  carried  on  by  the  farmer.  For 
this  purpose  the  liquid  obtained  from  dunghills  was 
placed  in  vessels  of  iron,  and  subjected  to  distilla- 
tion ;  the  product  of  this  distillation  was  converted 
into  muriate  of  ammonia  by  the  common  method. 
(Demachy.)  But  it  is  evident  that  such  a  thought- 
less proceeding  must  be  wholly  relinquished,  since 
the  nitrogen  of  100  lbs.  of  sal-ammoniac  (which  con- 
tains 26  parts  of  nitrogen)  is  equal  to  the  quantity 
of  nitrogen  contained  in  1200  lbs.  of  the  grain  of 
wheat,  1480  lbs.  of  that  of  barley,  or  2755  lbs.  of 
hay.     (Boussingault.) 

The  carbonate  of  ammonia  formed  by  the  putrefac- 
tion of  urine,  can  be  fixed  or  deprived  of  its  volatil- 
ity in  many  ways. 

If  a  field  be  strewed  with  gypsum,  and  then  with 
putrefied  urine  or  the  drainings  of  dunghills,  all  the 
carbonate  of  ammonia  will  be  converted  into  the  sul- 
phate which  will  remain  in  the  soil. 


192  OF  MANURE. 

But  there  are  still  simpler  means  of  effecting  this 
purpose;  —  gypsum,  chloride  of  calcium  (bleaching 
salts),  sulphuric  or  muriatic  acid,  and  super-phos- 
phate of  lime,  are  all  substances  of  a  very  low  price, 
and  completely  neutralize  the  urine,  converting  its 
ammonia  into  salts  which  possess  no  volatility. 

If  a  basin,  filled  with  concentrated  muriatic  acid, 
is  placed  in  a  common  necessary,  so  that  its  surface 
is  in  free  communication  with  the  vapors  which  rise 
from  below,  it  becomes  filled  after  a  few  days  with- 
crystals  of  muriate  of  ammonia.  The  ammonia,  the 
presence  of  which  the  organs  of  smell  amply  testify, 
combines  with  the  muriatic  acid  and  loses  entirely 
its  volatility,  and  thick  clouds  or  fumes  of  the  salt 
newly  formed  hang  over  the  basin.  In  stables  the 
same  may  be  seen.  The  ammonia  that  escapes  in 
this  manner  is  not  only  entirely  lost,  as  far  as  our 
vegetation  is  concerned,  but  it  works  also  a  slow, 
though  not  less  certain  destruction  of  the  walls  of 
the  building.  For  when  in  contact  with  the  lime  of 
the  mortar,  it  is  converted  into  nitric  acid,  which 
gradually  dissolves  the  lime.  The  injury  thus  done 
to  a  building  by  the  formation  of  the  soluble  nitrates, 
has  received  (in  Germany)  a  special  name, —  salpe- 
terfrass. 

The  ammonia  emitted  from  stables  and  necessaries 
is  always  in  combination  with  carbonic  acid.  Car- 
bonate of  ammonia  and  sulphate  of  lime  (gypsum) 
cannot  be  brought  together  at  common  temperatures, 
without  mutual  decomposition.  The  ammonia  enters 
into  combination  with  the  sulphuric  acid,  and  the 
carbonic  acid  with  the  lime,  forming  compounds 
which  are  not  volatile,  and  consequently  destitute  of 
all  smell.  Now,  if  we  strew  the  floors  of  our  stables, 
from  time  to  time,  with  common  gypsum,  they  will 
lose  all  their  offensive  smell,  and  none  of  the  ammo- 
nia which  forms  can  be  lost,  but  will  be  retained  in 
a  condition  serviceable  as  manure. 

With  the  exception  of  urea,  uric  acid  contains 
more  nitrogen  than  any  other  substance  generated 


NIGHT-SOIL.  193 

by  the  living  organism ;  it  is  soluble  in  water,  and 
can  be  thus  absorbed  by  the  roots  of  plants,  and  its 
nitrogen  assimilated  in  the  form  of  ammonia,  and  of 
the  oxalate,  hydrocyanate,  or  carbonate  of  ammonia. 
It  would  be  extremely  interesting  to  study  the 
transformations  which  uric  acid  suffers  in  a  living 
plant.  For  the  purpose  of  experiment,  the  plant 
should  be  made  to  grow  in  charcoal  powder  pre- 
viously heated  to  redness,  and  then  mixed  with  pure 
uric  acid.  The  examination  of  the  juice  of  the  plant, 
or  of  the  component  parts  of  the  seed  or  fruit,  would 
be  a  means  of  easily  detecting  the  differences. 


NIGHT-SOIL. 


In  respect  to  the  quantity  of  nitrogen  contained 
in  excrements,  100  parts  of  the  urine  of  a  healthy 
man  are  equal  to  1300  parts  of  the  fresh  dung  of  a 
horse,  according  to  the  analyses  of  Macaire  and  Mar- 
cet,  and  to  600  parts  of  those  of  a  cow.  Hence  it 
is  evident  that  it  would  be  of  much  importance  to 
agriculture  if  none  of  the  human  urine  were  lost. 
The  powerful  effects  of  urine  as  a  manure  are  well 
known  in  Flanders,*  but  they  are  considered  in- 
valuable by  the  Chinese,  who  are  the  oldest  agricul- 
tural people  we  know.  Indeed,  so  much  value  is 
attachied  to  the  influence  of  human  excrements  by 
these  people,  that  laws  of  the  state  forbid  that  any 
of  them  should  be  thrown  away,  and  reservoirs  are 
placed  in  every  house,  in  which  they  are  collected 
with  the  greatest  care.  No  other  kind  of  manure 
is  used  for  their  corn-fields,  f 

*  See  the  article  "On  the  Agriculture  of  the  Netherlands,"  Journ. 
Royal  Jigri.  Soc.^  Vol.  II.  part  1,  page  43,  for  much  interesting  informa- 
tion on  this  subject. 

t  Davis,  in  his  History  of  China,  states  that  every  substance  con- 
vertible into  manure  is  diligently  husbanded.  '*  The  cakes  that  remain 
after  the  expression  of  their  vegetable  oils,  horns  and  hoofs  reduced  to 
powder,  together  with  soot  and  ashes,  and  the  contents  of  common 

17 


194  OF  MANURE. 

China  is  the  birthplace  of  the  experimental  art ; 
the  incessant  striving  after  experiments  has  con- 
sewers,  are  much  used.  The  plaster  of  old  kitchens,  which  in  China 
have  no  chimneys  but  an  opening  at  the  top,  is  much  valued;  so  that 
they  will  sometimes  put  a  new  plaster  on  a  kitchen  for  the  sake  of  the 
old."  The  ammonia  contained  in  the  fuel  forms  nitrate  of  lime  with 
the  lime  in  the  mortar.  "  All  sorts  of  hair  are  used  as  a  manure,  and 
barbers'  shavings  are  carefully  appropriated  to  that  purpose.  The 
annual  produce  must  be  considerable  in  a  country  where  some  hundred 
millions  of  heads  are  kept  constantly  shaved.  Dung  of  all  animals,  but 
more  especially  night  soil,  is  esteemed  above  all  others.  Being  some- 
times formed  into  cakes,  it  is  dried  in  the  sun,  and  in  this  state  becomes 
an  object  of  sale  to  farmers,  who  dilute  it  previous  to  use.  They  con- 
struct large  cisterns  or  pits,  lined  with  lime  plaster,  as  well  as  earthen 
tubs,  sunk  into  the  ground,  with  straw  over  them  to  prevent  evapora- 
tion, in  which  all  kinds  of  vegetables  and  animal  refuse  are  collected. 
These  being  diluted  with  a  sufficient  quantity  of  liquid,  are  left  to  under- 
go the  putrefactive  fermentation,  and  then  applied  to  the  land.  In  the 
case  of  every  thing  except  rice,  the  Chinese  seem  to  manure  the  plant 
itself  rather  than  the  soil,  supplying  it  copiously  with  their  liquid 
preparation." 

"The  Chinese  husbandman,"  observes  Sir  G.  Staunton,  (Embassy^ 
Vol.  II.,)  "  always  steeps  the  seeds  he  intends  to  sow  in  liquid  manure, 
until  they  swell,  and  germination  begins  to  appear,  which  experience 
has  taught  him  will  have  the  effect  of  hastening  the  growth  of  plants, 
as  well  as  of  defending  them  against  the  insects  hidden  in  the  ground 
in  which  the  seeds  are  sown.  To  the  roots  of  plants  and  fruit-trees, 
the  Chinese  farmer  applies  liquid  manure  likewise."* 

Lastly,  we  extract  the  following  from  a  communication  to  Professor 
Webster,  of  Harvard  College,  United  States .  —  "  Human  urine,  is,  if 
possible,  more  husbanded  by  the  Chinese  than  night-soil  for  manure ; 
every  farm,  or  patch  of  land  for  cultivation,  has  a  tank,  where  all  sub- 
stances convertible  into  manure  are  carefully  deposited,  the  whole 
made  liquid  by  adding  urine  in  the  proportion  required,  and  invariably 
applied  in  that  state."  This  is  exactly  the  process  followed  in  the 
Netherlands  :  see  Outlines  of  Flemish  Husbandry,  V^g^  22. 

'•  The  business  of  collecting  urine  and  night-soil  employs  an  im- 
mense number  of  persons,  who  deposit  tubs  in  every  house  in  the  cities 
for  the  reception  of  the  urine  of  the  inmates,  which  vessels  are  re- 
moved daily,  with  as  much  care  as  our  farmers  remove  their  honey  from 
the  hives." 

When  we  consider  the  immense  value  of  night-soil  as  a  manure,  it  is 
quite  astounding  that  so  little  attention  is  paid  to  preserve  it.  The 
quantity  is  immense  which  is  carried  down  by  the  drains  in  London  to 
the  River  Thames,  serving  no  other  purpose  than  to  pollute  its  waters. 
It  has  been  shown,  by  a  very  simple  calculation,  that  the  value  of 
the  manure  thus  lost  amounts  annually  to  several  millions  of  pounds 
sterling.  A  substance,  which  by  its  putrefaction  generates  miasmata, 
may,  by  artificial  means,  be  rendered  totally  inoffensive,  inodorous,  and 
transportable,  and  yet  prejudice  prevents  these  means  being  resorted 
to. —  Ed. 

*  These  statements  are  confirmed  by  others,  which  have  been  kindly  com- 
municated to  me  by  a  gentleman  whose  opportunities  for  observation  during 
a  residence  in  China  of  several  years,  w^ere  ample,  and  whose  liberality  and 
devotion  to  agriculture  and  horticulture  have  already  conferred  upon  the 
community  results  of  great  interest  and  value.  —  See  Appendix. 


NIGHT-SOIL.  195 

ducted  the  Chinese  a  thousand  years  since  to  dis- 
coveries, which  have  been  the  envy  and  admiration 
of  Europeans  for  centuries,  especially  in  regard  to 
dyeing  and  painting,  and  to  the  manufactures  of 
porcelain,  silk,  and  colors  for  painters.  These  we 
were  long  unable  to  imitate,  and  yet  they  were  dis- 
covered by  them  without  the  assistance  of  scientific 
principles ;  for  in  the  books  of  the  Chinese  we  find 
recipes  and  directions  for  use,  but  never  explanations 
of  processes. 

Half  a  century  suflSced  to  Europeans  not  only  to 
equal  but  to  surpass  the  Chinese  in  the  arts  and 
manufactures,  and  this  was  owing  merely  to  the  ap- 
plication of  correct  principles  deduced  from  the  study 
of  chemistry.  But  how  infinitely  inferior  is  the  agri- 
culture of  Europe  to  that  of  China!  The  Chinese 
are  the  most  admirable  gardeners  and  trainers  of 
plants,  for  each  of  which  they  understand  how  to 
prepare  and  apply  the  best-adapted  manure.  The 
agriculture  of  their  country  is  the  most  perfect  in 
the  world;  and  there,  where  the  climate  in  the  most 
fertile  districts  differs  little  from  the  European,  very 
little  value  is  attached  to  the  excrements  of  animals. 
With  us,  thick  books  are  written,  but  no  experiments 
instituted;  the  quantity  of  manure  consumed  by  this 
and  that  plant  is  expressed  in  hundredth  parts,  and 
yet  we  know  not  what  manure  is  ! 

If  we  admit  that  the  liquid  and  solid  excrements 
of  man  amount  on  an  average  to  IJ  lb.  daily  (|  lb. 
of  urine  and  J  lb.  faeces),  and  that  both  taken  to- 
gether contain  3  per  cent,  of  nitrogen,  then  in  one 
year  they  will  amount  to  647  lbs.,  w^hich  contain 
16*41  lbs.  of  nitrogen,  a  quantity  suflScient  to  yield 
the  nitrogen  of  800  lbs.  of  wheat,  rye,  oats,  or  of  900 
lbs.  of  barley.     (Boussingault.) 

This  is  much  more  than  it  is  necessary  to  add  to 
an  acre  of  land  in  order  to  obtain,  with  the  assistance 
of  the  nitrogen  absorbed  from  the  atmosphere,  the 
richest  possible  crop  every  year.  Every  town  and 
farm  might  thus  supply  itself  with  the  manure,  which, 


196  OF  MANURE. 

besides  containing  the  most  nitrogen,  contains  also 
the  most  phosphates  ;  and  if  rotation  of  the  crops 
were  adopted,  they  would  be  most  abundant.  By 
using,  at  the  same  time,  bones  and  the  lixiviated 
ashes  of  wood,  the  excrements  of  animals  might  be 
completely  dispensed  with. 

When  human  excrements  are  treated  in  a  proper 
manner,  so  as  to  remove  the  moisture  which  they 
contain  without  permitting  the  escape  of  ammonia, 
they  may  be  put  into  such  a  form  as  will  allow  them 
to  be  transported  even  to  great  distances. 

This  is  already  attempted  in  many  towns,  and  the 
preparation  of  night-soil  for  transportation  consti- 
tutes not  an  unimportant  branch  of  industry.  But 
the  manner  in  which  this  is  done  is  the  most  in- 
judicious which  could  be  conceived.  In  Paris,  for 
example,  the  excrements  are  preserved  in  the  houses 
in  open  casks,  from  which  they  are  collected  and 
placed  in  deep  pits  at  Montfaucon,  but  are  not  sold 
until  they  have  attained  a  certain  degree  of  dryness 
by  evaporation  in  the  air.  But  whilst  lying  in  the 
receptacles  appropriated  for  them  in  the  houses,  the 
greatest  part  of  their  urea  is  converted  into  car- 
bonate of  ammonia;  lactate  and  phosphate  of  am- 
monia are  also  formed,  and  the  vegetable  matters 
contained  in  them  putrefy ;  all  their  sulphates  are 
decomposed,  whilst  their  sulphur  forms  sulphuretted 
hydrogen  and  hydro-sulphate  of  ammonia.  The  mass, 
when  dried  by  exposure  to  the  air,  has  lost  more 
than  half  of  the  nitrogen  which  the  excrements 
originally  contained  ;  for  the  ammonia  escapes  into 
the  atmosphere  along  with  the  water  which  evapo- 
rates ;  and  the  residue  now  consists  principally  of 
phosphate  of  lime,  with  phosphate  and  lactate  of 
ammonia,  and  small  quantities  of  urate  of  magnesia 
and  fatty  matter.  Nevertheless,  it  is  still  a  very 
powerful  manure,  but  its  value  as  such  would  be 
twice  or  four  times  as  great,  if  the  excrements  before 
being  dried  were  neutralized  with  a  cheap  mineral 
acid. 


NIGHT-SOIL.  197 

In  other  manufactories  of  manure  the  night-soil, 
whilst  still  soft,  is  mixed  with  the  ashes  of  wood,  or 
with  earth,*  both  of  which  substances  contain  a  large 
quantity  of  caustic  lime,  by  means  of  which  a  com- 
plete expulsion  of  all  its  ammonia  is  effected,  and  it 
is  completely  deprived  of  smell.  But  such  a  residue 
applied  as  manure  can  act  only  by  the  phosphates 
which  it  still  contains,  for  all  the  ammoniacal  salts 
have  been  decomposed  and  their  ammonia  expelled. 

The  preparation  of  night-soil  is  now  carried  on 
in  London  to  a  considerable  extent.  Owing  to  the 
variable  nature  of  the  climate,  artificial  means  are 
employed  in  its  desiccation.  The  night-soil,  after 
being  subjected  to  one  or  other  of  the  modes  of 
treatment  described  below,  is  placed  upon  iron  plates 
heated  by  means  of  furnaces. 

As  soon  as  the  night-soil  is  collected,  it  is  placed 
in  large  broad  trenches,  until  a  sufficient  quantity  is 
accumulated  for  the  purposes  of  the  manufacturer. 
But  here  it  undergoes  the  same  process  of  putrefac- 
tion to  which  allusion  has  been  made,  and  acquires  a 
peculiarly  offensive  smell  from  the  evolution  of  sul- 
phuretted hydrogen  and  other  gases,  which  are 
observed  to  escape.  Unless  some  means  be  em- 
ployed, at  this  stage  of  the  process,  to  retain  the 
ammonia,  it  escapes  into  the  atmosphere  in  the  form 
of  a  carbonate.  Various  methods  have  been  proposed 
to  effect  this  purpose.  Some  manufacturers  mix  the 
night-soil  with  chloride  of  lime,  and  evaporate  off 
the  water  by  the  aid  of  heat.  This  possesses  the 
advantage  of  depriving  the  excrements  of  smell, 
and  at  the  same  time  partially  fixes  the  ammonia 
which  would  otherwise  escape.  Chloride  of  lime 
always  contains  a  considerable  excess  of  lime;  hence 
part  of  the  ammonia  contained  in  the  night-soil  is 
expelled  by  means  of  it. 

More  simple  and  economical  methods  might  be 
employed.     A  patent,  which  has  been  taken  out  for 

*  This  is  practised  in  the  vicinity  of  large  cities  in  the  United 
States. 

17* 


198  OF  MANURE. 

the  preparation  of  this  useful  manure  states  in  its 
specification,  that  the  night-soil  is  to  be  mixed  with 
calcined  mud  and  finely-divided  charcoal.  By  this 
means,  the  smell  is  completely  and  instantaneously 
removed,  and  the  ammonia  retained  by  virtue  of  the 
aflSnity,  which  alumina  and  charcoal  exert  for  that 
compound.  This  plan  is  both  simple  and  efifiicacious, 
but  the  ammonia  is  apt  to  be  expelled  by  the  appli- 
cation of  the  heat  employed  in  drying  the  manure. 
The  addition  of  a  cheap  mineral  acid  to  the  night- 
soil,  before  admixture  with  these  ingredients,  would 
materially  improve  both  of  the  above  processes. 

It  would  no  doubt  be  highly  advantageous  in  the 
preparation  of  manures,  to  prepare  them  so  that 
they  contained  all  the  ingredients  necessary  for  the 
supply  of  the  plants  to  which  they  are  applied.  But 
these  w^ill  of  course  vary  according  to  the  nature  of 
the  soils  and  plants  for  which  they  are  intended. 
Thus  bones,  soap-boilers'  waste,  nitrate  of  soda, 
and  ashes  of  wood,  will  often  be  found  to  form 
advantageous  additions.  Sulphate  of  magnesia  (Ep- 
som salts)  would,  in  most  cases,  form  an  invaluable 
ingredient  in  prepared  night-soil.  (See  Supplemen- 
tary Chapter  on  Soils.)  The  products  of  the  decom- 
position proceeding  from  the  action  of  this  salt  upon 
night-soil  are,  sulphate  of  ammonia,  phosphate  of 
magnesia,  and  the  double  phosphate  of  magnesia 
and  ammonia.  Now  all  these  salts  exert  a  very 
favorable  influence  upon  vegetation,  and  the  phos- 
phate of  magnesia  is,  in  many  cases,  perfectly  indis- 
pensable to  the  growth  and  development  of  certain 
plants.  This  suggestion  is  well  worthy  of  the 
attention  of  the  farmer. 

Perhaps  the  best  and  most  practical  method  of 
fixing  the  ammoniacal  salts  of  urine  and  night-soil, 
is  to  mix  them  with  the  ashes  of  peat  or  coal.  When 
the  latter  are  employed,  care  must  be  taken  to  select 
such  as  are  of  a  porous,  earthy  consistence.  The 
ashes  both  of  peat  and  coal  contain  in  general  mag- 
nesia; hence  their  value  as  an  ingredient  of  prepared 


GUANO.  199 

night-soil.  When  magnesia  is  not  present,  it  will 
be  necessary  to  add  some  magnesian  limestone  or 
Epsom  salts.  The  night-soil  should  be  mixed  thor- 
oughly with  the  ashes,  and  exposed  to  the  air  to 
dry.  The  disagreeable  smell  is  thus  quickly  removed, 
and  a  pulverulent  manure  obtained,  which  can  be 
applied  to  the  fields  with  facility.* 

Animal  charcoal,  which  has  served  for  the  discol- 
oration of  sugar,  possesses  the  property  of  removing 
the  offensive  smell  of  night-soil,  and  is  of  itself  an 
admirable  manure.  In  cases  where  it  can  be  pro- 
cured with  facility,  it  will  be  found  to  add  to  the 
efficacy  of  the  latter.f 


GUANO. 


The  sterile  soils  of  the  South  American  coast  are 
manured  with  a  substance  called  guano,  consisting 
of  urate  of  ammonia  and  other  ammoniacal  salts,  by 
the  use  of  which  a  luxuriant  vegetation  and  the 
richest  crops  are  obtained.  Guano  has  lately  been 
imported  in  considerable  quantity  into  Liverpool  and 
several  other  English  ports,  and  is  now  experi- 
mentally employed  as  a  manure  by  English  agricul- 
turists. A  consideration  of  its  composition  and 
mode  of  action  cannot,  therefore,  fail  to  be  accept- 
able. 

Much  speculation  has  arisen  as  to  the  true  origin 
of  Guano, J  but  the  most  certain  proof  is  now  af- 
forded, that  it  has   been   produced  by  the  accumula- 

*  Night  soil  deprived  of  its  odor  and  rendered  portable  is  termed 
poudrette.  One  mode  of  preparing  it,  practised  in  France,  is  by  boiling 
the  refuse  matter  of  slaughter-houses,  by  steam,  into  a  thick  soup  ana 
then  mixing  the  whole  into  a  stiff  paste  with  sifted  coal  ashes,  and 
drying.  Tt  is  almost  one  half  animal  matter.  If  putrefaction  should 
have  begun,  the  addition  of  ashes,  sweetens  the  whole,  and  the  pre- 
pared "animalized  coal,"  as  it  is  termed,  is  as  sweet  to  the  nose,  as 
garden  mould. — Dana. 

t  For  an  account  of  Mr.  Daniell's  artificial  manure,  see  Appendix. 

I  Much  of  the  information  regarding  Guano  here  given  is  extracted 
from  a  paper  in  Liehig's  Mnnalerif  xxxvii.  3,  291. 


200  OF  MANURE. 

tion  of  the  excrements  of  innumerable  sea-fowl, 
which  inhabit  the  islands  upon  which  it  is  found. 
Meyen,  the  latest  writer  upon  this  subject,  completely 
coincides  with  this  opinion;  for  he  says*  —  "Their 
number  is  Legion ;  they  completely  cloud  the  sun, 
when  they  rise  from  their  resting-place  in  the  morn- 
ing in  flocks  of  miles  in  length."  Yet,  notwith- 
standing their  great  number,  thousands  of  years 
must  have  elapsed,  before  the  excrements  could 
have  accumulated  to  such  a  thickness  as  they  pos- 
sess at  present.  Guano  has  been  used  by  the  Peru- 
vians as  a  manure  since  the  twelfth  century;  and 
its  value  was  considered  so  inestimable,  that  the 
government  of  the  Incas  issued  a  decree,  by  which 
capital  punishment  was  inflicted  upon  any  person 
found  destroying  the  fowl  on  the  Guano  islands. 
Overseers  were  also  appointed  over  each  province, 
for  the  purpose  of  insuring  them  further  protection. 
Under  this  state  of  things,  the  accumulation  of  the 
excrements  may  have  well  taken  place.  All  these 
regulations  are,  however,  now  abandoned.f  Rivero 
states,  that  the  annual  consumption  of  guano  for  the 
purposes  of  agriculture  amounts  to  40,000  fanegas. 
The  increase  of  crops  obtained  by  the  use  of  guano 
is  very  remarkable.  According  to  the  same  authority, 
the  crop  of  potatoes  is  increased  45  times  by  means 
of  it,  and  that  of  maize  35  times.  The  manner  of 
applying  the  manure  is  singular.  Thus  in  Arica, 
where  so  much  pepper  {^Capsicum  haccatum)  is  cul- 
tivated, each  plant  is  manured  three  times :  first 
upon  the  appearance  of  the  roots,  second  upon  that 
of  the  leaves,  and  lastly  upon  the  formation  of  the 
fruit.  (Humboldt.)  From  this  it  will  be  observed, 
that  the  Peruvians  follow  the  plan  of  the  Chinese, 
in  manuring  the  plant  rather  than  the  soil.  The 
composition  of  guano  points  out  how  admirably  it  is 
fitted  for  a  manure ;    for   not   only  does   it  contain 

*  Reise  um  die  Erde,  B.  i.  S.  434. 

t  Garcilaso,  Historic  de  los  YncaSj  Vol.  I.  p.  134. 


GUANO.  20 1 

ammoniacal  salts  in  abundance,  but  also  those  inor- 
ganic constituents  which  are  indispensable  for  the 
development  of  plants. 

The  most  recent  analysis  is  that  of  Volckel,  who 
found  it  to  consist  of 

Urate  of  Ammonia  ....  9*0 

Oxalate  of  Ammonia  .         .         .  10-6 

Oxalate  of  Lime  .         *         .         .  7-0 

Phosphate  of  Ammonia         .         .         .  6*0 

Phosphate  of  Magnesia  and  Ammonia    .  2*6 

Sulphate  of  Potash       ....  5*5 

Sulphate  of  Soda  .        .        .        .  3"8 

Sal-ammoniac       .....  4*2 

Phosphate  of  Lime  ....  14-3 

Clay  and  sand  .....  4-7 
Organic  substances  not  estimated,  con-^ 

taining  12  per  cent,  of  matter  insolu-  I  oo.o 

ble  in  water.     Soluble  Salts  of  Iron  [ 

in  small  quantity.     Water      .         .     J 


lOO.O 

It  will  be  observed  from  the  above  analysis,  that 
urea  does  not  enter  into  the  composition  of  guano. 
The  uric  acid  of  the  excrements  must  have  been 
decomposed  into  oxalic  acid  and  ammonia.  The 
soluble  substances  contained  in  guano  amount  to 
half  its  weight.  It  is  singular  that  we  do  not  find 
nitrates  amongst  the  ingredients  which  compose  it. 
Guano  possesses  a  urinous  smell,  precisely  similar 
to  that  perceived  on  the  evaporation  of  urine.  The 
,  experiments  upon  the  efficacy  of  this  manure  in 
England  have  not  yet  been  sufficiently  multiplied  to 
enable  us  to  judge  whether  or  not  its  virtues  have 
been  overrated. 

The  corn-fields  in  China  receive  no  other  manure 
than  human  excrements.  But  we  cover  our  fields 
every  year  with  the  seeds  of  weeds,  which  from 
their  nature  and  form  pass  undigested  along  with 
the  excrements  through  animals,  without  being  de- 
prived of  their  power  of  germination,  and  yet  it  is 
considered  surprising  that  where  they  have  once 
flourished,  they  cannot  again  be  expelled  by  all  our 
endeavors  :  we  think  it  very  astonishing,  while  we 
really  sow  them   ourselves   every  year.      A  famous 


202  OF  MANURE. 

botanist,  attached  to  the  Dutch  embassy  to  China, 
could  scarcely  find  a  single  plant  on  the  corn-fields 
of  the  Chinese,  except  the  corn  itself. "^ 

The  urine  of  horses  contains  less  nitrogen  and 
phosphates  than  that  of  man.  According  to  Four- 
croy  and  Vauquelin  it  contains  only  five  per  cent,  of 
solid  matter,  and  in  that  quantity  only  0*7  of  urea ; 
whilst  100  parts  of  the  urine  of  man  contain  more 
than  four  times  as  much. 

The  urine  of  a  cow  is  particularly  rich  in  salts  of 
potash ;  but  according  to  Rouelle  and  Brande,  it  is 
almost  destitute  of  salts  of  soda.  The  urine  of 
swine  contains  a  large  quantity  of  the  phosphate  of 
magnesia  and  ammonia;  and  hence  it  is  that  concre- 
tions of  this  salt  are  so  frequently  found  in  the 
urinary  bladders  of  these  animals. 

It  is  evident,  that  if  we  place  the  solid  or  liquid 
excrements  of  man  or  the  liquid  excrements  of 
animals  on  our  land,  in  equal  proportion  to  the 
quantity  of  nitrogen  removed  from  it  in  the  form  of 
plants,  the  sum  of  this  element  in  the  soil  must 
increase  every  year;  for  to  the  quantity  which  we 
thus  supply,  another  portion  is  added  from  the 
atmosphere.  The  nitrogen  which  we  export  as  corn 
and  cattle,  and  which  is  thus  absorbed  by  large 
towns,  serves  only  to  benefit  other  farms,  if  we  do 
not  replace  it.  A  farm  which  possesses  no  pastures, , 
and  not  fields  sufficient  for  the  cultivation  of  fodder, 
requires  manure  containing  nitrogen  to  be  imported 
from  elsewhere,  if  it  is  desired  to  produce  a  full 
crop.  In  large  farms,  the  annual  expenditure  of 
nitrogen  is  completely  replaced  by  means  of  the 
pastures. 

The  only  absolute  loss  of  nitrogen,  therefore,  is 
limited  to  the  quantity  which  man  carries  with  him 
to  his  grave ;  but  this  at  the  utmost  cannot  amount 
to  more  than  3  lbs.  for  every  individual,  and  is  being 
collected  during  his  whole  life.     Nor  is  this  quantity 

*  Ingenhouss  on  the  Nutrition  of  Plants,  page  129  (German  edition). 


VALUE  OF  URINE.  203 

lost  to  plants,  for  it  escapes  into  the  atmosphere  as 
ammonia  during  the  putrefaction  and  decay  of  the 
body. 

A  high  degree  of  culture  requires  an  increased 
supply  of  manure.  With  the  abundance  of  the 
manure,  the  produce  in  corn  and  cattle  will  augment, 
but  must  diminish  with  its  deficiency. 

From  the  preceding  remarks  it  must  be  evident, 
that  the  greatest  value  should  be  attached  to  the 
liquid  excrements  of  man  and  animals,  when  a  ma- 
nure is  desired  which  shall  supply  nitrogen  to  the 
soil.  The  greatest  part  of  a  superabundant  crop, 
or,  in  other  words,  the  increase  of  growth  which  is 
in  our  power,  can  be  obtained  exclusively  by  their 
means. 

When  it  is  considered  that  with  every  pound  of 
ammonia  which  evaporates  a  loss  of  60  lbs.  of  corn 
is  sustained,  and  that  with  every  pound  of  urine  a 
pound  of  wheat  might  be  produced,  the  indifference 
with  which  these  liquid  excrements  are  regarded  is 
quite  incomprehensible.  In  most  places  only  the 
solid  excrements  impregnated  with  the  liquid  are 
used,  and  the  dunghills  containing  them  are  pro- 
tected neither  from  evaporation  nor  from  rain.  The 
solid  excrements  contain  the  insoluble,  the  liquid  all 
the  soluble  phosphates,  and  the  latter  contain  like- 
wise all  the  potash  which  existed  as  organic  salts  in 
the  plants  consumed  by  the  animals. 

Fresh  bones,  wool,  hair,  hoofs,  and  horn,  are  ma- 
nures containing  nitrogen  as  well  as  phosphates, 
and  are  consequently  fit  to  aid  the  process  of  vege- 
table life.  All  animal  matter  is  fitted  for  the  same 
purpose.  Butchers'  offal,  such  as  the  blood  and 
intestines  of  animals,  form  a  most  powerful  manure. 
It  is  in  general  necessary  to  dilute  such  manure  by 
admixture  with  other  kinds  less  powerful  in  their 
action. 

One  hundred  parts  of  dry  bones  contain  from  32 
to  33  per  cent,  of  dry  gelatine;  now  supposing  this 
to  contain  the   same  quantity  of  nitrogen  as  animal 


204  OF  MANURE. 

glue,  viz.,  5'28  per  cent.,  then  100  parts  of  bones 
must  be  considered  as  equivalent  to  250  parts  of 
human  urine. 

Bones  may  be  preserved  unchanged  for  thousands 
of  years,  in  dry  or  even  in  moist  soils,  provided  the 
access  of  rain  is  prevented  ;  as  is  exemplified  by 
the  bones  of  antediluvian  animals  found  in  loam  or 
gypsum,  the  interior  parts  being  protected  by  the 
exterior  from  the  action  of  water.  But  they  become 
warm  when  reduced  to  a  fine  powder,  and  moistened 
bones  generate  heat  and  enter  into  putrefaction;  the 
gelatine  which  they  contain  is  decomposed,  and  its 
nitrogen  converted  into  carbonate  of  ammonia  and 
other  ammoniacal  salts,  which  are  retained  in  a 
great  measure  by  the  powder  itself.  (Bones  burnt 
till  quite  white,  and  recently  heated  to  redness, 
absorb  7*5  times  their  volume  of  pure  ammoniacal 
gas.) 


ARTIFICIAL    MANURES. 

We  have  now  examined  the  action  of  the  animal 
or  natural  manures  upon  plants  ;  but  it  is  evident, 
that  if  artificial  manures  contain  the  same  constitu- 
ents, they  will  exercise  a  similar  action  upon  the 
plants  to  which  they  are  applied.  We  shall  only 
notice  here  one  or  two  of  those  principally  employed. 

Since  it  has  been  ascertained  that  animal  manures 
act  (as  far  as  the  formation  of  organic  matter  is 
concerned)  only  by  the  ammonia  which  they  contain, 
attention  has  been  devoted  by  chemists  to  discover 
a  more  economical  means  of  presenting  this  ammonia 
to  plants.  The  water  which  distils  from  the  retorts 
in  the  preparation  of  coal  gas  is  strongly  charged 
with  this  alkali,  but  is  at  the  same  time  mixed  with 
tar  and  other  empyreumatic  impurities.  It  has  been 
customary  to  allow  the  tarry  matter  to  subside,  and 
decant  off  the  clear,  supernatant  liquor.    This  liquor, 


LIQUOR  OF  GAS-WORKS.  205 

being  diluted  to  such  a  degree  as  to  be  tasteless,  is 
applied  as  a  manure  to  the  field.* 
I       Now,  the  ammoniacal  liquor  of  the  gas-works  con- 
j  tains    the    ammonia  in   the   form   of  carbonate   and 
'  hydro-sulphate  of  ammonia  (sulphuret  of  ammonium). 
I  The  latter  compound  is  a  deadly  poison  to  vegeta- 
I  bles,  nor  can  we  conceive  that  by  dilution  its  prop- 
erties can  be  changed.     The  carbonate  of  ammonia 
is   volatile,  and   escapes  into   the   atmosphere.     To 
obviate  this  latter  inconvenience  and  render  it  more 
transportable,  it  has  been  proposed  to  convert  the 
carbonate  into  the  sulphate,  by  means  of  gypsum,  f 
But   this   does   not   remove   the   hydro-sulphate.     A 
more  simple  and  efficacious  method  is  to  add  a  solu- 
tion of  sulphate  of  iron  (the  green  vitriol  of  the  shops) 
to  the  liquor,  until  no  further  precipitation  ensues. 
Sulphuret   and   carbonate  of  iron   are  thus   formed, 
and  the  whole  of  the  ammonia  enters  into  combina- 
tion w4th  the   sulphuric  acid,  and  forms  sulphate  of 
ammonia.     Care  must  be  taken  to  avoid  too  great  an 
excess  of  sulphate  of  iron ;  and  the  liquor  thus  pre- 
pared should  be  freely  exposed  to  the  air  to  promote 
the  oxidation. 

The  liquor  still,  however,  contains  empyreumatic 
matters,  which  are  injurious  to  plants.  These  may 
he  removed  by  evaporating  the  liquor  to  dryness, 
and  heating  the  residue  to  incipient  redness.  By 
this  means  they  are  rendered  insoluble,  and  the  sul- 
phate of  ammonia  is  not  affected,  unless  the  heat  has 
been  carried  too  far.  The  liquor  properly  diluted 
has  been  found  very  advantageous,  even  without  the 
removal  of  the  empyreumatic  matter. 

*  Mr.  Blake,  who  has  charge  of  the  gas- work  in  Boston,  informs  me, 
that  one  chaldron  (2700  lbs.  of  Pictou  coal,  yields,  on  the  average,  33 
gallons  of  ammoniacal  liquor  containing  about  5  per  cent,  of  dry  am- 
monia ;  and  by  passing  the  gases  generated  from  this  quantity  of  coal 
through  a  solution  of  proto-sulphate  of  iron,  he  has  obtained  in  addition 
24  gallons  of  a  solution  containing  about  4  per  cent,  of  dry  ammonia. 
About  4  chaldrons  of  coal  are  used  per  diem,  at  the  gas-works  in  Boa- 
ton,  and  200  gallons  of  liquor,  containing  from  4  to  5  per  cent,  of  am- 
monia, could  be  furnished  daily  at  small  cost.  —  }V, 

t  Three  Lectures  on  Agriculture,  by  Dr.  Daubeny,  page  87. 

18 


206^  OF  MANURE. 

Nitrate  of  soda  has  lately  engaged  much  attention, 
and  is  supposed  to  exert  its  favorable  action  upon 
vegetation  by  yielding  nitrogen  to  those  constitu- 
ents of  plants  which  contain  it.  The  experiments 
which  have  hitherto  been  instituted  with  this  ma- 
nure do  not  warrant  us  in  concluding  with  positive 
certainty  that  it  is  the  nitrogen  alone  to  which  it 
owes  its  efficacy,  but  they  certainly  render  this  a 
plausible  explanation  of  its  virtues.  Thus  Mr. 
Pusey,  the  late  able  president  of  the  Royal  Agri- 
cultural Society,  has  shown,  that  the  same  effects 
are  produced  by  putrefied  urine,  soot,  gas-liquor, 
and  nitrate  of  soda.*  Now  the  three  former  act  by 
virtue  of  the  ammonia  which  enters  into  their  com- 
position. The  usual  effects  produced  by  these  and 
nitrate  of  soda  are  to  increase  the  intensity  of  the 
green  coloring  matter,  to  augment  the  quantity  of 
straw,  but  to  produce  a  light  grain.  Mr.  Hyettf 
has  communicated  the  results  of  an  analysis  of  two 
samples  of  w^heat  grown  under  similar  circumstances, 
one  of  which  had  been  treated  with  nitre,  the  other 
not.  The  former  contained  23*25  per  cent,  of  gluten, 
and  1.375  of  albumen ;  the  latter  only  19  per  cent, 
of  gluten,  and  0.62  of  albumen.  Here  the  azotized 
matters  appear  to  have  considerably  increased  in 
quantity.  There  is  nothing  opposed  to  the  sup- 
position that  nitric  acid  may  be  decomposed  by 
plants,  and  its  nitrogen  assimilated.  We  find  that 
vegetables  possess  the  power  of  decomposing  car- 
bonic acid,  and  of  appropriating  its  carbon  for  their 
own  use.  Now  this  acid  is  infinitely  more  difficult 
to  decompose  than  nitric  acid.  But  there  are  other 
circumstances  which  oppose  the  adoption  of  the  view 
that  nitrate  of  soda  acts  by  virtue  of  the  nitrogen 
w^hich  enters  into  its  composition.  Were  this  the 
case,  the  action  should  be  more  uniform  than  it  has 
hitherto  been  found  to  be.  On  some  soils  the  salt 
does  not   possess  the  smallest  influence;  whilst  on 

*  Journal  of  the  Roval  Agricultural  Society,  Vol.  II.  p.  123. 
i  Ibid.,  Vol.  II.  p.  143. 


NITRATE  OF  SODA.  207 

others  it  affords  great  benefit.  We  can  only  furnish 
an  explanation  of  this  seeming  caprice  by  a  reference 
to  the  chemical  composition  of  the  soil  upon  which 
I  it  is  applied.  If  the  advantages  attending  the  ap- 
i  plication  of  nitrate  of  soda  are  due  to  the  alkaline 
I  base  which  it  contains,  then  it  is  evident  that  this 
manure  can  be  of  small  value  on  soils  containing  a 
quantity  of  alkalies  sufficient  for  the  purposes  of  the 
plants  grown  upon  them;  whilst,  on  the  other  hand, 
such  as  are  deficient  in  these  must  experience  benefit 
through  its  means.*  In  certain  cases  in  which  ni- 
trate of  soda  has  failed,  nitrate  of  potash  (common 
saltpetre)  has  been  very  successful.  Analyses  of 
wheat  grown  with  nitrate  of  soda  and  nitrate  of  pot- 
ash would  be  of  interest,  in  order  to  determine 
whether  a  mutual  substitution  of  their  respective 
bases  is  effected.  It  is  to  be  hoped  that  future  ex- 
periments will  throw  more  light  upon  the  action  of 
this  interesting  manure,  for  theory  cannot  be  satisfied 
with  those  already  existing.  It  has  been  usual  to 
employ  a  less  quantity  by  weight  of  nitrate  of  pot- 
ash than  of  nitrate  of  soda.  This  procedure  seems 
rather  empirical,  for  unless  sanctioned  by  experience, 
it  would  a  priori  appear  to  be  better  to  add  the 
greatest  quantity  of  that  salt  which  possesses  the 
highest  equivalent.  Now  the  equivalent  of  nitrate  of 
potash  is  considerably  higher  than  that  of  nitrate 
of  soda. 

Charcoal  in  a  state  of  powder  must  be  considered 
as  a  very  powerful  means  of  promoting  the  growth 
of  plants  on  heavy  soils,  and  particularly  on  such 
as  consist  of  argillaceous  earth.  \ 

*  General  Sir  Howard  Elphinstone  informs  me,  that  he  found  car- 
bonate of  soda  (soda  ash)  an  excellent  manure  for  his  land.  The  crops 
obtained  by  means  of  it  presented  the  same  general  characters  as  those 
manured  with  nitrate  of  potash,  and  exhibited  a  greater  intensity  of 
color.  If  this  is  found  uniformly  to  be  the  case,  it  will  very  much 
strengthen  the  supposition  that  the  action  of  nitrate  of  soda  is  due  to 
its  alkaline  constituent  —  Ed. 

t  For  much  valuable  information  on  the  subject  of  manures,  see 
"Agricultural  Chemistry,"  Vol.  VIII.  of  Sir  H.  Davy's  collected 
Works. 


208  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

Ingenhouss  proposed  dilute  sulphuric  acid  as  a 
means  of  increasing  the  fertility  of  a  soil.  Now, 
when  this  acid  is  sprinkled  on  calcareous  soils,  gyp- 
sum (sulphate  of  lime)  is  immediately  formed,  which 
of  course  prevents  the  necessity  of  manuring  the 
soils  with  this  material.  100  parts  of  concentrated 
sulphuric  acid  diluted  with  from  800  to  1000  parts 
of  water,  are  equivalent  to  176  parts  of  gypsum. 


SUPPLEMENTARY   CHAPTER. 

ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

The  fertility  of  a  soil  is  much  influenced  by  its 
physical  properties,  such  as  its  porosity,  color,  attrac- 
tion for  moisture,  or  state  of  disintegration.  But 
independently  of  these  conditions,  the  fertility  de- 
pends upon  the  chemical  constituents  of  which  the 
soil  is  composed. 

We  have  already  shown,  at  considerable  length, 
that  those  alkalies,  earths,  and  phosphates,  which 
constitute  the  ashes  of  plants,  are  perfectly  indis- 
pensable for  their  development ;  and  that  plants 
cannot  flourish  upon  soils  from  which  these  com- 
pounds are  absent.  The  necessity  of  alkalies  for 
the  vital  processes  of  plants  will  be  obvious,  when 
we  consider  that  almost  all  the  different  families  of 
plants  are  distinguished  by  containing  certain  acids, 
diff*ering  very  much  in  composition ;  and  further, 
that  these  acids  do  not  exist  in  the  juice  in  an 
isolated  state,  but  generally  in  combination  with 
certain  alkaline  or  earthy  bases.  The  juice  of  the 
vine  contains  tartaric  acid,  that  of  the  sorrel  oxalic 
acid.  It  is  quite  obvious,  that  a  peculiar  action  must 
be  in  operation  in  the  organism  of  the  vine  and 
sorrel,  by  means  of  which  the  generation  of  tartaric 
and  oxalic  acid  is  effected  ;  and  also  that  the  same 
action  must  exist  in  all  plants  of  the  same  genus. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  209 

A  similar  cause  forces  corn-plants  to  extract  silicic 
acid  from  the  soil.  The  number  of  acids  found 
in  different  plants  is  very  numerous,  but  the  most 
common  are  those  which  we  have  already  mentioned; 
to  which  may  be  added  acetic,  malic,  citric,  aconitic, 
maleic,  kinovic  acids,  &c. 

When  we  observe  that  the  proper  acids  of  each 
family  of  plants  are  never  absent  from  it,  we  must 
admit  that  the  plants  belonging  to  that  family  could 
not  attain  perfection,  if  the  generation  of  their 
peculiar  acids  were  prevented.  Hence,  if  the  pro- 
duction of  tartaric  acid  in  the  vine  were  rendered 
impossible,  it  could  not  produce  grapes,  or  in  other 
words,  would  not  fructify.  Now  the  generation  of 
organic  acids  is  prevented  in  the  vine,  and,  indeed, 
in  all  plants  which  yield  nourishment  to  men  and 
animals,  when  alkalies  are  absent  from  the  soil  in 
which  they  grow.  The  organic  acids  in  plants  are 
very  rarely  found  in  a  free  state ;  in  general,  they 
are  in  combination  with  potash,  soda,  lime,  or  mag- 
nesia. Thus,  silicic  acid  is  found  as  silicate  of 
potash,  acetic  acid  as  acetate  of  potash  or  soda, 
oxalic  acid  as  oxalate  of  potash,  soda,  or  lime,  tar- 
taric acid  as  bitartrate  of  potash,  &c.  The  potash, 
soda,  lime,  and  magnesia  in  these  plants  are,  there- 
fore, as  indispensable  for  their  existence  as  the 
carbon  from  which  their  organic  acids  are  produced. 

In  order  not  to  form  an  erroneous  conclusion  re- 
garding the  processes  of  vegetable  nutrition,  it  must 
be  admitted  that  plants  require  certain  salts  for  the 
sustenance  of  their  vital  functions,  the  acids  of 
which  salts  exist  either  in  the  soil  (such  as  silicic  or 
phosphoric  acids)  or  are  generated  from  nutriment 
derived  from  the  atmosphere.  Hence,  if  these  salts 
are  not  contained  in  the  soil,  or  if  the  bases  neces- 
sary for  their  production  be  absent,  they  cannot  be 
formed;  or  in  other  words,  plants  cannot  grow  in 
such  a  soil.  The  juice,  fruit,  and  leaves  of  a  plant 
cannot  attain  maturity,  if  the  constituents  necessary 
for  their  formation   are  wanting,  and   salts  must  be 

18* 


210  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

viewed  as  such.  These  salts  do  not,  however,  occur 
simultaneously  in  all  plants.  Thus,  in  saline  plants, 
soda  is  the  only  alkali  found ;  in  corn  plants,  lime 
and  potash  form  constituents.  Several  contain  both 
soda  and  potash,  some  both  potash  and  lime ;  whilst 
others  contain  potash  and  magnesia.  The  acids 
vary  in  a  similar  manner.  Thus  one  plant  may 
contain  phosphate  of  lime,  a  second,  phosphate  of 
magnesia,  a  third,  an  alkali  combined  with  silicic 
acid,  and  a  fourth,  an  alkali  in  combination  with  a 
vegetable  acid.  The  respective  quantities  of  the 
salts  required  b}^  plants  are  very  unequal.  The 
aptitude  of  a  soil  to  produce  one,  but  not  another 
kind  of  plant,  is  due  to  the  presence  of  a  base  w^hich 
the  former  requires,  and  the  absence  of  that,  indis- 
pensable for  the  development  of  the  latter.  Upon 
the  correct  knowledge  of  the  bases  and  salts  requi- 
site for  the  sustenance  of  each  plant,  and  of  the 
composition  of  the  soil  upon  which  it  grows,  depends 
the  whole  system  of  a  rational  theory  of  agriculture; 
and  that  knowledge  alone  can  explain  the  process 
of  fallow,  or  furnish  us  with  the  most  advantageous 
methods  of  affording  plants  their  proper  nourish- 
ment. 

Give,  —  so  says  the  rational  theory,  —  to  one  plant 
such  substances  as  are  necessary  for  its  development, 
but  spare  those,  which  are  not  requisite,  for  the 
production  of  other  plants  that  require  them. 

It  is  the  same  with  regard  to  these  bases  as  it  is 
with  the  water  which  is  necessary  for  the  roots  of 
various  plants.  Thus,  whilst  one  plant  flourishes 
luxuriantly  in  an  arid  soil,  a  second  requires  much 
moisture,  a  third  finds  necessary  this  moisture  at 
the  commencement  of  its  development,  and  a  fourth 
(such  as  potatoes)  after  the  appearance  of  the  blos- 
som. It  would  be  very  erroneous  to  present  the 
same  quantity  of  water  to  all  plants  indiscriminately. 
Yet  this  obvious  principle  is  lost  sight  of  in  the 
manuring  of  plants.  An  empirical  system  of  agri- 
culture has   administered  the  same  kind  of  manures 


ON  THE  CHEMICAL  CONSTITXJENTS  OF  SOILS.  211 

to  all  plants ;  or  when  a  selection  has  been  made,  it 
was  not  based  upon  a  knowledge  of  their  peculiar 
characters  or  composition. 

The  cost  of  labor  in  England  has  given  rise  to 
the  production  of  much  ingenuity  in  the  invention 
of  machines,  which  have  produced  improvements  in 
the  mode  of  application  of  manures.  In  order  to 
use  these  with  advantage,  pulverulent  manures  are 
employed,  instead  of  the  common  stable  manure, 
which  is  generally  mixed  with  much  straw. 

The  necessity  for  such  forms  of  manure  naturally 
suggested  the  employment  of  bone  dust,  dried  dung, 
lime,  ashes,  &c.  Now,  although  by  these  means  the 
necessary  phosphates  are  furnished  to  a  soil,  and 
solid  animal  excrements  rendered  unnecessary,  they 
have  led  to  the  neglect  of  the  liquid  excrements, 
that  is,  of  the  urine  of  men  and  animals,  which  is 
thus  completely  lost  to  agriculture.  For  although 
the  meadows  receive,  during  autumn  and  winter, 
when  cattle  are  fed  upon  them,  the  solid  and  liquid 
excrements  of  these  animals,  yet  the  urine  of  man, 
into  which  all  the  nitrogenous  constituents  of  ani- 
mals are  finally  deposited,  is  completely  lost  to  the 
fields.  This  most  important  of  all  manures,  so  pro- 
perly estimated  in  Flanders,  Germany,  and  China,  is 
altogether  lost  to  the  English  agriculturist.  In  large 
towns  it  is  either  allowed  to  run  into  the  rivers,  or 
sink  into  the  ground  in  such  a  manner  as  to  be  of  no 
benefit  to  the  vegetable  kingdom. 

The  most  important  growth  in  England  is  that  of 
wheat ;  then  of  barley,  oats,  beans,  and  turnips.  Po- 
tatoes are  only  cultivated  to  a  great  extent  in  certain 
localities  ;  rye,  beet-root,  and  rape-seed,  not  very 
generally.  Lucern  is  only  known  in  a  few  districts, 
whilst  red  clover  is  found  universally.  Now,  the  se- 
lection of  inorganic  manures  for  these  plants  may  be 
fixed  upon  by  an  examination  of  the  composition  of 
their  ashes.  Thus  wheat  must  be  cultivated  in  a  soil 
rich  in  silicate  of  potash.  If  this  soil  is  formed  from 
feldspar,  mica,  basalt,  clinkstone,  or  indeed  of  any 


212  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

minerals  which  disintegrate  with  facility,  crops  of 
wheat  and  barley  may  be  grown  upon  it  for  many 
centuries  in  succession.  But,  in  order  to  support  an 
uninterrupted  succession,  the  annual  disintegration 
must  be  sufficiently  great  to  render  soluble  a  quanti- 
ty of  silicate  of  potash  sufficient  for  the  supply  of  a 
full  crop  of  wheat  or  barley.  If  this  is  not  the  case, 
the  soil  must  either  be  allowed  to  lie  fallow  from 
time  to  time,  or  plants  may  be  cultivated  upon  it 
which  contain  little  silicate  of  potash,  or  the  roots 
of  which  are  enabled  to  penetrate  deeper  into  the 
soil  than  corn  plants  in  search  of  this  salt.  During 
this  interval  of  repose,  the  materials  of  the  soil  dis- 
integrate, and  potash  in  a  soluble  state  is  liberated 
on  the  layers  exposed  to  the  action  of  the  atmo- 
sphere. When  this  has  taken  place,  rich  crops  of 
wheat  may  be  again  expected. 

The  alkaline  phosphates,  as  well  as  the  phosphates 
of  magnesia  and  lime,  are  necessary  for  the  produc- 
tion of  all  corn-plants.  Now,  bones  contain  the  latter, 
but  none  of  the  former  salts.  These  must,  therefore, 
be  furnished  by  means  of  night-soil,  or  of  urine,  a 
manure  which  is  particularly  rich  in  them.*  Wood 
ashes  have  been  found  very  useful  for  wheat  in  cal- 
careous soils  ;  for  these  ashes  contain  both  phos- 
phate of  lime  and  silicate  of  potash.  In  like  man- 
ner stable  manure  and  night-soil  render  clayey  soils 
fertile,  by  furnishing  the  magnesia  in  which  they  are 
deficient.  The  ashes  of  all  kinds  of  herbs  and  de- 
cayed straw  are  capable  of  replacing  wood  ashes. 

A  compost  manure,  which  is  adapted  to  furnish  all 
the  inorganic  matters  to  wheat,  oats,  and  barley,  may 
be  made,  by  mixing  equal  parts  of  bone  dust  and  a 
solution  of  silicate  of  potash  (known  as  soluble  glass 
in  commerce),  allowing  this  mixture  to  dry  in  the 
air,  and  then  adding  10  or  12  parts  of  gypsum,  with 
16  parts  of  common  salt.     Such  a   compost  would 

*  It  has  been  already  stated  that  bran  contains  phosphate  of  soda  and 
phosphate  of  magnesia,  so  that  it  is  useful  as  a  manure  where  phos- 
phates are  desired.  —  Ed. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  213 

render  unnecessary  the  animal  manures,  which  act 
by  their  inorganic  ingredients.  According  to  Ber- 
thier,  100  parts  of  the  ashes  of  wheat  straw  con- 
tain, — 

Of  matter  soluble  in  water 9*0 

Of  matter  insoluble  in  water       .         .         .         .  91-0 

Now  100  parts  of  the  soluble  matter  contain, — 

Carbonic  acid         ......  a  trace 

Sulphuric  acid 20 

Muriatic  acid 130 

Silica .  350 

Potash  and  Soda 500 

1000 

100  parts  of  the  insoluble  matter  contain, — 

Carbonic  acid  .  .  .  .  .0 

Phosphoric  acid      .  .  .  .  .1*2 

Silica    . 75  0 

Lime  ......  5-8 

Oxide  of  Iron  and  Charcoal     ....  10-0 

Potash         ......  8-0 

100-0 

The  silicate  of  potash  employed  in  the  preparation 
of  the  compost  described  above  must  not  deliquesce 
on  exposure  to  the  air,  but  must  give  a  gelatinous 
consistence  to  the  water  in  which  it  is  dissolved,  and 
dry  to  a  w^hite  powder  by  exposure.  It  is  only  at- 
tractive of  moisture  when  an  excess  of  potash  is 
present,  which  is  apt  to  exert  an  injurious  influence 
upon  the  tender  roots  of  plants.  In  those  cases 
where  silicate  of  potash  cannot  be  procured,  a  suffi- 
ciency of  wood  ashes  will  supply  its  place.* 

All  culinary  vegetables,  but  particularly  the  cruci- 


*  In  some  parts  of  the  grand  duchy  of  Hesse,  where  wood  is  scarce 
and  dear,  it  is  customary  for  the  common  people  to  club  together  and 
build  baking  ovens,  which  are  heated  with  straw  instead  of  wood.  The 
ashes  of  this  straw  are  carefully  collected  and  sold  every  year  at  very 
high  prices.  The  farmers  there  have  found  by  experience  that  the 
ashes  of  straw  form  the  very  best  manure  for  wheat;  although  it  exerts 
no  influence  on  the  growth  of  fallow-crops  (potatoes  or  the  leguminosaB, 
for  example).  The  stem  of  whe?t  grown  in  this  way  possesses  an  un- 
common strength.  The  cause  of  the  favorable  action  of  these  ashes 
will  be  apparent,  when  it  is  considered  that  all  corn  plants  require  sili- 
cate of  potash  ;  and  that  the  ashes  of  straw  consist  almost  entirely  of 
this  compound.  —  Ed. 


214  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

ferae,  such  as  mustard,  (^sinapis  alba  and  nigra,)  con- 
tain sulphur  in  notable  quantity.  The  same  is  the 
case  with  turnips,  the  different  varieties  of  rape,  cab- 
bage, celery,  and  red  clover.  These  plants  thrive 
best  in  soils  containing  sulphates ;  hence  if  these 
salts  do  not  form  natural  constituents  of  the  soil, 
they  must  be  introduced  as  manure.  Sulphate  of 
ammonia  is  the  best  salt  for  this  purpose.  It  is  most 
easily  procured  by  the  addition  of  gypsum  or  sul- 
phate of  iron  ^  (green  vitriol)  to  putrefied  urine. 

Horn,  wool,  and  hoofs  of  cattle,  contain  sulphur 
as  a  constituent,  so  that  they  will  be  found  a  valua- 
ble manure  when  administered  with  soluble  phos- 
phates, (with  urine,  for  example.) 

Phosphate  of  magnesia  and  ammonia  forms  the 
principal  inorganic  constituent  of  the  potato ;  salts 
of  potash  also  exist  in  it,  but  in  very  limited  quanti- 
ty. Now  the  soil  is  rendered  unfitted  for  its  culti- 
vation, even  though  the  herb  be  returned  to  it  after 
the  removal  of  the  crop,  unless  some  means  are 
adopted  to  replace  the  phosphate  of  magnesia  re- 
moved in  the  bulbous  roots.  This  is  best  effected 
by  mixtures  of  night-soil  with  bran,  magnesian  lime- 
stone, or  the  ashes  of  certain  kinds  of  coal.  I  ap- 
plied to  a  field  of  potatoes  manure,  consisting  of 
night-soil  and  sulphate  of  magnesia  (Epsom  salts), 
and  obtained  a  remarkably  large  crop.  The  manure 
was  prepared  by  adding  a  quantity  of  sulphate  of 
magnesia  to  a  mixture  of  urine  and  faeces,  and  mix- 
ing the  whole  with  the  ashes  of  coal  or  vegetable 
mould,  till  it  acquired  the  consistence  of  a  thick 
paste,  which  was  thus  dried  by  exposure  to  the  sun. 

It  has  been  formerly  mentioned,  that  the  seconda- 
ry and  tertiary  limestones  contain  potash  :  marl,  and 
the  calcareous  minerals  used  for  the  preparation  of 
hydraulic    mortar,    may    be    particularly    specified. 

*  If  sulphate  of  iron  be  employed,  it  ought  not  to  be  added  in  great 
excess,  and  the  urine  must  be  exposed  to  the  air  for  some  time  after, 
for  the  purpose  of  converting  the  iron  into  the  peroxide.  A  salt  of  the 
protoxide  of  iron  is  injurious  to  vegetation.  —  Ed. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  215 

These  have  been  found  to  form  excellent  manures 
for  heavy  clayey  soils,  particularly  for  such  as  disin- 
tegrate with  difficulty.  They  are  most  efficacious 
when  burnt,  but  can  only  be  applied  in  this  state 
after  harvest,  and  ought  to  be  ploughed  into  the  soil 
as  quickly  as  possible.  By  the  action  of  lime  upon 
clay,  the  potash  contained  in  the  latter  is  rendered 
soluble.  This  may  easily  be  shown  by  mixing  one 
part  of  marl  with  half  its  weight  of  burned  lime, 
adding  water,  and  setting  aside  the  mixture  to  re- 
pose for  some  time.  Even  after  a  space  of  24  hours, 
an  appreciable  quantity  of  potash  may  be  detected 
in  the  water.* 

A  most  striking  proof  of  the  influence  of  potash 
upon  vegetation  has  been  furnished  by  the  investi- 
gations of  the  "  administration  "  of  tobacco  in  Paris. 
For  many  years  accurate  analyses  of  the  ashes  of 
various  sorts  of  tobacco  have  been  executed,  by  the 
orders  of  the  "  administration " ;  and  it  has  been 
found,  as  the  result  of  these,  that  the  value  of  the 
tobacco  stands  in  a  certain  relation  to  the  quantity 
of  potash  contained  in  the  ashes.  By  this  means  a 
mode  was  furnished  of  distinguishing  the  different 
soils  upon  which  the  tobacco  under  examination  had 
been  cultivated,  as  well  as  the  peculiar  class  to 
which  it  belonged.  Another  striking  fact  was  also 
disclosed  through  these  analyses.  Certain  cele- 
brated kinds  of  American  tobacco  were  found  gradu- 
ally to  yield  a  smaller  quantity  of  ashes,  and  their 
value  diminished  in  the  same  proportion.  For  this 
information  I  am  indebted  to  M.  Pelouze,  professor 
of  the  Polytechnic  School  in  Paris. 

*  One  of  the  causes  of  the  advantages  produced  by  subsoil  ploughing 
is,  that  it  exposes  the  soil  to  the  disintegrating  influences  of  the  atmo- 
sphere. Hence  it  is  that  the  subsoil  plough  is  so  beneficial  in  siliceous 
soils,  and  exerts  no  apparent  effect  upon  those  which  contain  much 
clay.  The  former  disintegrate  and  liberate  their  potash  both  with  fa- 
cility and  rapidity  ;  whilst  the  disintegration  of  the  latter  proceeds  with 
slowness,  and  no  appreciable  effects  are  produced.  (See  Journal  of  the 
Agricultural  Society,  Vol.  II.  p.  27.)  It  is  probable,  however,  that  if 
the  land  received  a  dressing  of  lime  after  subsoil  ploughing,  the  effects 
would  be  produced  more  rapidly.  — Ed. 


216  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

There  are  certain  plants  which  contain  either  no 
potash,  or  mere  traces  of  it.  Such  are  the  poppy, 
(^papaver  somniferum,)  which  generates  in  its  organ- 
ism a  vegetable  alkaloid;  Indian  corn  (^zea  mays)] 
and  helianthus  tuherosus.  For  plants  such  as  these 
the  potash  in  the  soil  is  of  no  use,  and  farmers  are 
well  aw^are  that  they  can  be  cultivated  without  ro- 
tation on  the  same  soil,  particularly  when  the  herbs 
and  straw,  or  their  ashes,  are  returned  to  the  soil 
after  the  reaping  of  the  crop. 

One  cause  of  the  favorable  action  of  the  nitrates 
of  soda  and  potash  must  doubtless  be,  that  through 
their  agency  the  akalies  which  are  deficient  in  a  soil 
are  furnished  to  it.  Thus  it  has  been  found  that  in 
soils  deficient  in  potash,  the  nitrates  of  soda  or  pot- 
ash have  been  very  advantageous ;  whilst  those,  on 
the  other  hand,  w^hich  contain  a  sufficiency  of  alka- 
lies, have  experienced  no  beneficial  effects  through 
their  means.  In  the  application  of  manures  to  soils 
we  should  be  guided  by  the  general  composition  of 
the  ashes  of  plants,  whilst  the  manure  applied  to  a 
particular  plant  ought  to  be  selected  with  reference 
to  the  substances  which  it  demands  for  its  nourish- 
ment. In  general,  a  manure  should  contain  a  large 
quantity  of  alkaline  salts,  a  considerable  proportion 
of  phosphate  of  magnesia,  and  a  smaller  proportion 
of  phosphate  of  lime;  azotized  manure  and  ammonia- 
cal  salts  cannot  be  too  frequently  employed. 

In  the  following  part  of  this  chapter  I  shall  de- 
scribe a  number  of  analyses  of  soils  executed  by 
Sprengel,  together  with  observations  on  their  sterili- 
ty and  fertility,  as  stated  by  that  distinguished 
agriculturist.  It  is  unnecessary  to  describe  the  mo- 
dus operandi  used  in  the  analyses  of  these  soils,  for 
this  kind  of  research  will  never  be  made  by  farmers, 
who  must  apply  to  the  professional  chemist,  if  they 
wish  for  information  regarding  the  composition  of 
their  soils. 

Under  the  term  surface-soil,  we  mean  that  portion 
of  soil  w^hich  is  on  the  surface ;  whilst  by  subsoil  we 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  217 

mean  that   which   is  below  the  former,  and  out  of 
reach  of  the  ordinary  plough. 


CHEMICAL    COMPOSITION    OF    CERTAIN    SOILS,    ACCORDING    TO 

ANALYSIS. 

1.  Surface-soil  (A)  a  good  loamy  soil,  from  the 
vicinity  of  Gandersheim.  It  is  remarkable  for  pro- 
ducing uncommonly  fine  red  clover  when  manured 
with  gypsum.  (B)  is  an  analysis  of  the  subsoil. 
100  parts  contain  :  — 

(A)         (B) 

Silica,  with  fine  siliceous  sand       .        .  91-331  93883 

Alumina 1-344  1-944 

Peroxide  of  iron,  with  a  little  protoxide      1-562  2  226 

Peroxide  of  manganese  .  .  .  0*082  0*320 
Magnesia  and  silica,  in  combination  with 

sulphuric  acid  and  humus  .  .  .  0*800  0  720 
Magnesia,  with  silica  and  humic  acid 

combined         .        .         .         .        .        0*440  0*340 

Potash,  in  combination  with  silica  .  0*156  0*105 
Soda,  principally  in  combination  with 

silica,  and  a  little  as  common  salt        .    0*066  0*060 

Phosphoric  acid 0*098  01 90 

Sulphuric  acid  in  combination  with  lime  0111  0*012 

Chlorine  (in  common  salt)          .         .        0012  0*012 

Humus,  with  traces  of  azotized  matter  .    4100  0*184 

100000     100*000 

An  inspection  of  the  above  analyses  will  show 
that  the  soil  contains  a  very  small  proportion  of  salts 
of  sulphuric  acid, —  a  circumstance  which  accounts 
for  the  favorable  action  of  gypsum  upon  it. 

2.  The  surface-soil  (A)  is  a  fine-grained  loamy 
soil  from  Gandersheim,  distinguished  for  the  re- 
markably large  crops  of  beans,  peas,  tares,  &c., 
which  it  produces  when  manured  with  gypsum.  (B) 
is  the  analysis  of  the  subsoil.     100  parts  contain:  — 

(A)  (B) 

Silica,  with  fine  siliceous  sand        .         .  90*221  92-324" 

Alumina 2106  2  262 

Peroxide  and  protoxide  of  iron       .         .     3951  2  914 
Peroxide  of  manganese       .         .         .         0-960  2*960 
Lime,  principally  combined  with  phos- 
phoric acid  and  humus    .         .        .        0  539  0-532 

19 


218 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Magnesia,  with  silicate  of  potash,  &c.  .     0-730 

Potash 0-066 

Soda 0-010 

Phosphoric  acid 0*367 

Sulphuric  acid  (in  gypsum)  .         .  •  a  trace 

Chlorine  (in  common  salt)           .         .  0*100 

Humus  and  azotized  matter    .         .  .     0900 

Loss 0-140 


(B) 
0-340 
0-304 
a  trace 
0-122 
0-010 
0004 


0-228 


100-000     100000 

The  analysis  of  this  soil  shows,  that,  with  the  ex- 
ception of  gypsum,  every  ingredient  is  present 
which  is  requisite  for  the  nourishment  of  leguminous 
plants.  Hence  it  is  that  gypsum  exerts  such  a 
favorable  influence  upon  it. 

3.  Surface-soil  (A)  a  strong  loamy  sand, 
Brunswick.  (B)  the  analysis  of  the  subsoil, 
parts  contain  :  — 


from 
100 


Silica,  with  coarse  siliceous  sand  . 
Alumina    ..... 

Peroxide  and  protoxide  of  iron 

Peroxide  of  manganese 

Lime      ...... 

Magnesia  .... 

Potash  and  soda,  the  greatest  part  in 

combination  with  silica 
Phosphate  of  iron 
Sulphuric  acid  (in  gypsum)  . 
Chlorine  (in  common  salt) 
Humus 


(A) 

95-698 
0-504 
2-496 

a  trace 
0038 
0-147 

0-090 
0-164 
0007 
0-010 
0-846 


(B) 

96-880 
0-890 
1-496 

a  trace 
0019 
0-260 

0-079 

0110 

a  trace 

a  trace 

0-226 


100000      100000 

This  soil  was  much  improved  by  manuring  with 
lime  and  ashes.  It  was  then  found  well  fitted  for 
clover,  beans,  and  peas. 

4.  Surface-soil  (A)  a  loamy  sand,  from  the  envi- 
rons of  Brunswick.  (B)  analysis  of  the  subsoil  at 
the  depth  of  3  feet.     100  parts  contain  :  — 

(A)  (B) 
Silica  and  fine  siliceous  sand  .             .        94-724  97  340 
Alumina                .            .            .            .     1-638  0-806 
Protoxide  and  peroxide  of  iron  with  man- 
ganese  .....     1-960  1201 

Lime 1-028  0-296 

Magnesia  ....  a  trace  0095 

Potash  and  soda  .  .  .  0-077  0-112 

Phosphoric  acid    ....     0024  0-015 

Gypsum  ....  0.010  a  trace 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


219 


Chlorine  of  the  salt 
Humus 


(A) 
0-207 
0-512 


(B) 
a  trace 

0135 


100-000     100-000 


This  soil  produces  luxuriant  crops  of  lucern  and 
sainfoin,  as  well  as  of  all  other  plants  the  roots  of 
which  penetrate  deeply  into  the  ground.  The  rea- 
son is  apparent.  The  subsoil  contains  magnesia, 
which  is  wanting  in  the  surface-soil. 

5.  Surface-soil  (A)  a  loamy  sand,  from  the  envi- 
rons of  Brunswick.  (B)  analysis  of  the  subsoil  at  a 
depth  of  2  feet.      100  parts  contain  :  — 


Silica,  with  coarse  siliceous  sand 

Alumina 

Protoxide  and  peroxide  of  iron     . 

Peroxide  of  manganese 

Lime,  in  combination  with  silica 

Magnesia  in         do.  do. 

Potash  and  soda    . 

Phosphate  of  iron 

Sulphuric  acid       .  .        '     . 

Chlorine 

Humus  soluble  in  alkalies 

Humus  insoluble  in  alkalies  . 


(A) 

(B) 

.  95-843 

95-180 

0600 

1-600 

.     1-800 

2-200 

a  trace 

a  trace 

.     0-038 

0-455 

0-006 

0-160 

.    0-005 

0004 

0198 

0400 

.    0-002 

a  trace 

0-006 

0001 

.     1-000 

•   .   • 

0-502 

.   .   . 

100-000 

100-000 

This  soil  is  characterized  by  its  great  sterility. 
White  clover  could  not  be  made  to  grow  upon  it. 
The  obvious  cause  of  its  poverty  is  a  deficiency  of 
lime,  magnesia,  potash,  and  gypsum ;  for  we  find 
that  the  fertility  of  the  soil  was  much  increased  by 
manuring  it  with  marl.  The  white  clover,  which 
formerly  had  refused  to  grow  on  this  soil,  now  grew 
upon  it  with  much  luxuriance.  The  aridity  of  the 
soil  could  not  have  been  the  cause  of  its  sterility, 
for  the  stiff  nature  of  the  subsoil  on  which  it  rested 
prevented  a  deficiency  of  moisture. 

6.  Surface-soil  (A)  a  loamy  land  from  the  environs 
of  Brunswick.  (B)  the  analysis  of  the  subsoil,  at  a 
depth  of  2  feet.     100  parts  contain :  — 


(A) 

(B) 

Silica,  with  fine  siliceous  sand     . 

.  94-998 

96-490 

Alumina 

0-61O 

1-083 

Protoxide  and  peroxide  of  iron     . 

.    1 080 

1-472 

220  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


(A) 

(B) 

Peroxide  of  manganese 

0-268 

0-400 

Lime,  in  combination  with  silica 

.    0-141 

0-182 

Magnesia,  idem 

0-208 

0-205 

Potash,  idem 

.    0050 

0-070 

Soda,  idem 

0044 

0-050 

Phosphate  of  iron 

.    0086 

0-030 

Gypsum 

0041 

0005 

Common  salt 

.    0-004 

0-003 

Humus  soluble  in  alkalies 

0-400 

0010 

Humus  accompanied  by  azotized  matter 

2070 

•      •      • 

Resinous  matter 

• 

a  trace 

•      •      • 

100000 

100000 

This  soil  is  by  no  means  remarkable  for  its  steril- 
ity, but  is  decidedly  improved  by  manuring  with 
burned  ferruginous  loam.  It  is,  however,  rendered 
still  better  by  the  use  of  burned  marl,  —  a  manure 
which  is  rich  in  iron,  potash,  gypsum,  and  phosphate 
of  lime.  The  marl  does  not  exert  so  favorable  an 
action  when  applied  in  its  natural  state  ;  but  the  heat 
liberates  the  potash  from  the  insoluble  compound 
which  it  forms  with  silica. 

7.  Surface-soil  (A)  a  loamy  sand,  from  Brunswick. 
(B)  analysis  of  the  subsoil  at  a  depth  of  IJ  feet.  100 
parts  contain :  — 

Silica,  with  fine  siliceous  sand     . 

Alumina  .... 

Protoxide  and  peroxide  of  iron     . 

Peroxide  of  manganese 

Lime,  combined  with  silica 

Magnesia,  idem 

Potash,  idem 

Soda,  idem       .... 

Phosphate  of  iron 

Sulphuric  acid  contained  in  gypsum 

Chlorine  .... 

Humus  soluble  in  alkalies 

Humus,  with  azotized  organic  remains 


(A) 

(B) 

.  92-980 

96-414 

0-820 

1-000 

.     1-666 

1-370 

0-188 

0-240 

,    0748 

0-364 

0-168 

0160 

,    0-065 

0045 

0-130 

0082 

.    0246 

0043 

a  trace 

0-005 

a  trace 

0-007 

0764 

0-270 

2225 

.   .   . 

100-000 

100-000 

This  soil  when  manured  with  gypsum  is  very  fa- 
vorable to  the  production  of  leguminous  plants  and 
red  clover.  But  it  is  very  remarkable,  on  account  of 
the  rust  which  always  attacks  the  corn  p]E;*nts  which 
may  be  grown  upon  it.  This  rust  and  mildew  (uredo 
linearis,  jpucdnia  graminis)  is  a  disease  which  at- 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


221 


tacks  the  stem  and  leaves,  and  is  quite  different  from 
the  brand  {uredo  glumarum)  which  appears  on  the 
seeds  and  organs  of  reproduction.  Rust  is  most  fre- 
quently detected  on  plants  growing  on  soils  which 
contain  bog-ore,  or  turf  iron-ore.  According  to 
Sprengel,  rust  contains  phosphate  of  iron,  to  which 
this  chemist  ascribes  the  origin  of  the  disease.  It 
is  very  possible  that  other  causes  may  operate  in  the 
production  of  similar  diseases. 

8.  Soil,  a  fine-grained  loamy  marl,  from  the  vicin- 
ity of  Schoningen.  It  produces  corn,  which  is,  how- 
ever, very  liable  to  blight.      100  parts  contain  :  — 


Silica,  with  siliceous  sand    . 

.            . 

.  93'870 

Alumina 

.            . 

1-248 

Protoxide  and  peroxide  of  iron 

.    1-418 

Peroxide  of  manganese  . 

.            • 

0-360 

Lime  (principally  carbonate) 

•            • 

.    0-546 

Magnesia,  idem  . 

•            . 

0-560 

Potash,  with  silica    . 

.            • 

.    0-050 

Soda,  with  silica 

.            • 

0-040 

Phosphate  of  iron 

«                                 4 

.    0-246 

Sulphuric  acid  with  lime 

.                                 . 

0-027 

Carbonic  acid,  with  lime  and 

magnesia 

.     1-145 

Humus  soluble  in  alkalies 

•            . 

0-400 

Humus 

• 

.    0-090 

100-000 

It  will  be  observed  that  a  considerable  quantity  of 
phosphate  of  iron  is  contained  in  this  soil,  and  the 
corn  which  grows  upon  it  is,  as  in  the  former  case, 
disposed  to  rust. 

9.  Surface-soil  (A)  a  loamy  soil,  from  Brunswick, 
remarkable  on  account  of  producing  buck-wheat, 
which  is  exceedingly  poor  in  the  grain.  (B)  analy- 
sis of  the  subsoil  at  a  depth  of  IJ  foot.  100  parts 
contain:  — 


Silica,  with  coarse  siliceous  sand 

Alumina  .... 

Protoxide  and  peroxide  of  iron     . 

Protoxide  and  peroxide  of  manganese 

Lime,  in  combination  with  silica 

Magnesia,  idem 

Potash,  with  silica  . 

Soda     ..... 

Phosphate  of  iron 

Sulphuric  acid  with  lime 

19* 


(A) 

(B) 

95-114 

92-458 

1080 

2-530 

1-900 

2502 

0-320 

0-920 

0380 

0-710 

0-300 

0-551 

0020 

0120 

0004 

0-034 

0052 

0175 

0-006 

a  trace 

222 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Chlorine  (in  common  salt) 
Humus  soluble  in  alkalies 
Humus 


(A) 
0.005 
0-619 
0-200 


(B) 
a  trace 


100-000    100000 


By  manuring  the  land  with  wood  ashes,  the  soil  is 
enabled  to  produce  buck-wheat,  with  rich  grain  ;  the 
leguminous  plants  also  thrive  luxuriantly  upon  it. 
This  increased  fertility  is  due  to  the  ashes,  by  means 
of  which  both  potash  and  phosphates  are  supplied  to 
the  land. 

10.  Subsoil  of  a  loamy,  sandy  soil,  from  Brunswick. 
•It  is  remarkable  for  having  produced  excellent  crops 
of  hops  for  a  long  series  of  years.  100  parts,  by 
weight,  consist  of:  — 


Silica,  with  siliceous  sand        , 

95-660 

Alumina                  .             .             •            . 

.      1-586 

Protoxide  and  peroxide  of  iron 

1-616 

Peroxide  of  manganese      .             , 

.      0-240 

Lime,  in  combination  with  silica 

0083 

Magnesia                 .            .            .            • 

.      0080 

Potash                .... 

0030 

Soda            .             .             .             .             . 

.      0-220 

Phosphoric  acid             .            •            • 

0039 

Sulphuric  acid        .             •            .            • 

.      0-003 

Chlorine             .... 

a  trace 

Humus  soluble  in  alkalies 

.      0-080 

Humus               .... 

0-360 

100000 

Although  the  hops  contain  a  large  quantity  of 
potash,  soda,  phosphoric  acid,  sulphuric  acid,  lime, 
and  magnesia,  yet  we  do  not  find  that  these  exist 
in  the  soil  in  superabundant  quantity.  Nor  is  it 
necessary  that  they  should,  for  the  roots  of  the  hops 
penetrate  8  or  10  feet  deep  into  the  soil,  and  search 
out  the  materials  jfitted  to  nourish  the  plants.  Hence 
it  is  that  hops  thrive  well  on  soils  comparatively 
poor  in  their  proper  ingredients.  The  same  is  the 
case  with  all  plants  of  a  similar  nature,  the  roots  of 
which  possess  a  tendency  to  extend  in  search  of 
food;  we  see  this  particularly  in  lucern  and  sainfoin. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  223 


SOILS    OF    HEATHS. 

11.  Soil  of  a  heath  converted  into  arable  land,  in 
the  vicinity  of  Brunswick.  It  is  naturally  sterile, 
but  produces  good  crops  when  manured  with  lime, 
marl,  cow-dung,  or  the  ashes  of  the  heaths  which 
grow  upon  it. 

Silica,  and  coarse  siliceous  sand  .  .  71*504 
Alumina  .....  0*780 
Protoxide  and  peroxide  of  iron,  principally  com- 
bined with  humus  .  .  .  0*420 
Peroxide  of  manganese,  idem  .  .  .  0*220 
Lime,  idem  ....  0*1 34 
Magnesia,  idem  .....  0032 
Potash  and  soda  principally  as  silicates  .  0*058 
Phosphoric  acid,  (principally  as  phosphate  of  iron)  0*115 
Sulphuric  acid  (in  gypsum)  ,  .  .  0*018 
Chlorine  (in  common  salt)  .  .  ,  0014 
Humus  soluble  in  alkalies  .  ,  .  9"820 
Humus,  with  vegetable  remains  .  .  14*975 
Resinous  matters                ....  1*910 


100000 

Ashes  of  the  soil  of  the  heath,  before  being  con- 
verted into  arable  land:  — 

Silica,  with  siliceous  sand  .  .  .  92*641 
Alumina  .....  1*352 
Oxides  of  iron  and  manganese  .  .  3.324 
Lime,  in  combination  with  sulphuric  and  phos- 
phoric acids  .....  0*929 
Magnesia,  combined  with  sulphuric  acid  .  0*283 
Potash  and  soda  (principally  as  sulphates  and 

phosphates)          .....  0*564 

Phosphoric  acid,  combined  with  lime               .  0250 

Sulphuric  acid,  with  potash,  soda,  and  lime         .  1*620 

Chlorine  in  common  salt          .            .            .  0*037 


100.000 

12.  Surface-soil  of  a  fine-grained  loam,  from  the 
vicinity  of  Brunswick.  It  is  remarkable  from  the 
circumstance,  that  not  a  single  year  passes  in  which 
corn  plants  are  cultivated  upon  it  without  the  stem 
of  the  plants  being  attacked  by  rust.  Even  the 
grain  is  covered  with  a  yellow  rust,  and  is  much 
shrunk.      100  parts  of  the  soil  contain:  — 

Silica  and  fine  siliceous  sand  .  .  87  859 

Alumina  .....      2652 

Peroxide  of  iron  with  a  large  proportion  of  protoxide  5*  132 


224  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Protoxide  and  peroxide  of  manganese  .  0*840 

Lime  principally  combined  with  silica      .  .  1*459 

Magnesia  idem  ....  0*280 

Potash  and  soda  idem         ....  0*090 

Phosphoric  acid  in  combination  with  iron       .  0*505 

Sulphuric  acid  in  combination  with  lime  .  0*068 

Chlorine  in  common  salt  ,  .  .  0*006 

Humus       ......  1*109 


100-000 

This  soil  does  not  suffer  from  want  of  drainage : 
it  is  well  exposed  to  the  sun,  is  in  an  elevated  situa- 
tion, and  in  a  good  state  of  cultivation.  In  order 
to  ascertain  whether  the  rust  was  due  to  the  con- 
stituents of  the  soil,  (phosphate  of  iron  ?)  or  to  cer- 
•  tain  fortuitous  circumstances  unconnected  with  their 
operation,  a  portion  of  the  land  was  removed  to 
another  locality,  and  made  into  an  artificial  soil  of 
fifteen  inches  in  depth.  Upon  this  barley  and  wheat 
were  sown ;  but  it  was  found,  as  in  the  former  case, 
that  the  plants  were  attacked  by  rust,  whilst  barley 
growing  on  the  land  surrounding  this  soil  was  not 
at  all  affected  by  the  disease.  From  this  experiment 
it  follows,  that  certain  constituents  in  the  soil  favor 
the  development  of  rust. 

13.  Soil  of  a  heath,  which  had  been  brought  into 
cultivation  in  the  vicinity  of  Brunswick.  The  analy- 
sis was  made  before  any  kind  of  crops  had  been 
grown  upon  it.  Corn-plants  were  first  reared  upon 
the  new  soil,  but  were  found  to  be  attacked  by  rust, 
even  on  those  parts  which  had  been  manured  respec- 
tively with  lime,  marl,  potash,  wood  ashes,  bone-dust, 
ashes  of  the  heath  plant,  common  salt,  and  ammonia. 
100  parts  contain :  — 

Silica  with  coarse  siliceous  sand          .            .  51.337 

Alumina                  .             .             .             .  .       0528 
Protoxide  and  peroxide  of  iron  in  combination 

with  phosphoric  and  humic  acids     .             .  0*398 

Protoxide  and  peroxide  of  manganese      .  .      0  005 

Lime  in  combination  with  humus        .            .  0230 

Magnesia  idem       .            .             .          ' .  .      0-040 

Potash  and  soda             .             .             .             .  0*010 

Phosphoric  acid               .    .            .            .  .      0066 

Sulphuric  acid               ....  0*022 

Chlorine                  .             .             .            .  .      0*014 

Humus  soluble  in  alkalies        .            .            .  13*210 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  225 

Resinous  matters  ....      2-040 

Coal  of  humus  and  water         .  .  .  32- 100 


100000 

The  next  analysis  represents  the  soil  after  being 
burnt.  100  parts  by  weight  of  the  soil  left  after 
ignition  only  60  parts.  100  parts  of  these  ashes 
consisted  of:  — 

Silica  and  siliceous  sand           .            .            .  95-204 

Alumina                  .....  1*640 

Peroxide  of  iron            ....  1  -344 

Peroxide  of  manganese     ....  0*080 

Lime  in  combination  with  sulphuric  acid       .  0-544 

Magnesia  combined  with  silica                  .            .  0*465 

Potash  and  soda            ....  0052 

Phosphoric  acid  (principally  as  phosphate  of  iron)  0*330 

Sulphuric  acid               ....  0322 

Chlorine                  .            ....  0019 


100*000 
By  comparing  this  analysis  with  the  one  which 
has  preceded  it,  an  increase  in  certain  of  the  con- 
stituents is  observed,  particularly  with  respect  to 
the  sulphuric  acid,  potash,  soda,  magnesia,  oxide  of 
iron,  oxide  of  manganese,  and  alumina.  From  this 
it  follows,  that  the  humus,  or  in  other  words,  the 
vegetable  remains,  must  have  contained  a  quantity 
of  these  substances  confined  within  it,  in  such  a 
manner  that  they  were  not  exhibited  by  analysis. 

Oats  and  barley  were  sown  on  this  land  the 
second  year  after  being  reclaimed,  and  both  suffered 
much  from  rust,  although  different  parts  of  the  soil 
were  manured  with  marl,  lime,  and  peat-ashes ;  whilst 
other  portions  were  left  without  manure.  In  the 
first  year,  all  the  different  parts  of  the  field  pro- 
duced potatoes,  but  they  succeeded  best  in  those 
divisions  which  had  been  manured  with  peat-ashes, 
lime  and  marl.  In  the  second  year,  oats  mixed  with 
a  little  barley  were  sown  upon  the  soil;  and  the 
straw  was  found  to  be  strongest  on  the  parts  treated 
with  peat-ashes,  lime,  marl,  and  ashes  of  wood.  Red 
clover  was  sown  on  the  third  year ;  it  appeared  in 
best  condition  on  those  portions  of  the  soil  manured 
with  marl  and  lime.     Upon  the  divisions  of  the  field 


226  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

which  had  been  left  without  manure,  as  well  as  on 
those  manured  with  bone-dust,  potash,  ammonia,  and 
common  salt,  the  clover  scarcely  appeared  above 
ground.  The  divisions  of  the  field,  which  had  been 
manured  in  the  first  year  with  peat-ashes,  ammonia, 
and  ashes  of  wood,  were  sown  with  buckwheat  after 
the  removal  of  the  first  crop  of  clover.  The  buck- 
wheat succeeded  very  well  on  all  the  divisions,  yet 
a  marked  difference  was  perceptible  in  favor  of  the 
portion  treated  with  ammonia.  These  experiments 
show  us,  that  a  dressing  of  lime  did  not  completely 
remove  from  the  soil  its  tendency  to  impart  rust  to 
the  plants  grown  upon  it.  Nevertheless  it  is  highly 
probable,  that  as  soon  as  the  protoxide  of  iron 
became  converted  into  the  peroxide  by  exposure  to 
the  atmosphere,  lime  would  possess  more  power  in 
decomposing  the  phosphate  of  iron. 

14.  Subsoil  of  a  loamy  soil  in  the  vicinity  of 
Brunswick.  It  is  remarkable  from  the  circumstance 
that  sainfoin  cannot  be  cultivated  upon  it  more  than 
two  or  three  years  in  succession.  The  portion 
analyzed  was  taken  from  a  depth  of  five  feet.  100 
parts  contained :  — 


Silica  with  very  fine  siliceous  sand 

90-035 

Alumina 

• 

.      1-976 

Peroxide  of  iron 

4700 

Protoxide  of  iron 

• 

,      1115 

Protoxide  and  peroxide  of  manganese 

0-240 

Lime            .... 

■ 

.      0-022 

Magnesia           .... 

0-115 

Potash  and  soda 

• 

.      0-300 

Phosphoric  acid,  combined  with  iron  . 

0098 

Sulphuric  acid  (the  greatest  part  in  combina 

tion 

with  protoxide  of  iron) 

1-399 

Chlorine 

• 

.    a  trace 

100000 

Now  the  results  of  the  analysis  give  a  sufficient 
account  of  the  failure  of  the  sainfoin.  The  soil 
contains  above  one  per  cent,  of  sulphate  of  the  pro- 
toxide of  iron  (^green  vitriol  of  commerce),  a  salt 
which  exerts  a  poisonous  action  upon  plants.  Lime 
is   not   present  in  quantity  sufficient   to   decompose 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  227 

this  salt.  Hence  it  is  that  sainfoin  will  not  thrive 
on  this  soil,  nor  indeed  lucern,  or  any  other  of  the 
plants  with  deep  roots.  The  evil  cannot  be  obviated 
by  any  methods  sufficiently  economical  for  the  far- 
mer, because  the  soil  cannot  be  mixed  with  lime  at  a 
depth  of  five  or  six  feet.  For  many  years  experi- 
ments have  been  made  in  vain,  in  order  to  adapt  this 
soil  for  sainfoin  and  lucern,  and  much  expense  in- 
curred, which  could  all  have  been  saved,  had  the 
soil  been  previously  analyzed.  This  example  affords 
a  most  convincing  proof  of  the  importance  of  chemi- 
cal knowledge  to  an  agriculturist. 

15.  Surface-soil  (A)  of  a  sandy  loam  in  the  vicini- 
ty of  Brunswick,  celebrated  for  its  beautiful  crops 
of  clover,  rye,  potatoes,  and  barley.  The  clover 
must,  however,  always  be  manured  with  gypsum. 
(B)  is  an  analysis  of  the  subsoil  at  the  depth  of  1| 
foot.      100  parts  contain  :  — 

(A)  (B) 

Silica  with  coarse  siliceous  sand        .         .    94-274  95146 

Alumina 1-560  1-416 

Peroxide  of  iron  with  a  little  phosphoric  acid  2*496  2-528 

Peroxide  of  manganese     ....      0*240  0320 

Lime 0*400  0  297 

Magnesia 0-230  0  221 

Potash  and  soda     .         .         .         .         .  0102  0  060 

Sulphuric  acid 0*039  0-012 

Chlorine 0-005  a  trace 

Humus  soluble  in  alkaline  carbonates       .      0-444  .    .   . 

Humus 0-210  .    .   . 

100000      100-000 

The  best  property  of  this  soil  is,  that  its  inferior 
layers  are  nearly  of  the  same  composition  as  the 
superior,  as  far  as  the  inorganic  constituents  are 
concerned.  It  is  a  soil  upon  which  the  plants 
mentioned  above  will  seldom  fail ;  and  as  it  posses- 
ses a  very  good  mixture  to  the  depth  of  four  or  five 
feet,  it  would,  doubtless,  produce  lucern  also. 

16.  Surface-soil  (A)  of  a  sandy  loam  in  the  vicinity 
of  Brunswick.  It  produces  excellent  crops  of  oats 
and  clover,  when  the  latter  is  manured  with  gypsum. 


228 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


(B)  Analysis  of  the  subsoil  taken  from  a  depth  of 
1|  foot.     100  parts  contain  :  — 


Silica  and  siliceous  sand 

Alumina  ..... 

Peroxide  of  iron  with  a  little  phosphoric  acid 

Peroxide  of  manganese 

Lime,  principally  combined  with  silica 

Magnesia,  idem        .... 

Potash    ..... 

Soda  ..... 

Sulphuric  acid   .... 

Chlorine        ..... 

Humus   ..... 


(A) 

(B) 

94-430 

89-660 

1.474 

0980 

2-370 

7-616 

a  trace 

a  trace 

0-680 

0954 

0-290 

0-520 

0190> 
0010  s 

0150 

a  trace 

a  trace 

0015 

a  trace 

0-541 

0120 

100-000 

100-000 

Both  the  surface  and  the  sub-soil  contain  only 
traces  of  sulphuric  acid.  Hence  the  application  of 
gypsum  is  attended  with  great  benefit.  Without 
doubt,  marl  and  lime  will  be  found  of  essential 
service. 

17.  Soil  from  the  environs  of  Brunswick,  consisting 
principally  of  sand,  and  eminently  remarked  for  its 
sterility.  It  was,  however,  much  improved  by  ma- 
nuring it  with  marl  which  contained  24  per  cent,  of 
lime,  together  with  magnesia,  manganese,  potash, 
soda,  gypsum,  and  common  salt.  100  parts  of  the 
soil  contained :  — 


Silica  and  siliceous  sand    .            . 

.    95-841 

Alumina            .... 

0-600 

Protoxide  and  peroxide  of  iron 

.      1800 

Peroxide  of  manganese 

a  trace 

Lime  in  combination  with  silica   . 

.      0  038 

Magnesia,  idem 

0006 

Potash         ..... 

.      0-002 

Soda      ..... 

0-003 

Phosphoric  acid  combined  with  iron 

.      0198 

Sulphuric  acid 

0-002 

Chlorine     ..... 

.      0006 

Humus              .            .            . 

1-504 

100  000 


Here  another  proof  is  presented,  that  a  soil  may 
be  very  rich  in  humus  and  yet  be  very  poor  as  re- 
gards fertility.  By  means  of  the  marl,  the  inorganic 
ingredients  of  the  plants  are  furnished  to  the  soil, 
which  contains  them  in  very  small  quantity. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  229 

18.  The  soil  of  a  very  fertile  loam  from  the  vicin- 
ity of  Walkenried.      100  parts  contain:  — 

Silica,  with  coarse-grained  siliceous  sand          .  88-456 

Alumina         ......  0-650 

Peroxide  and  protoxide  of  iron,  accompanied  by  much 

magnetic  iron  sand           ....  5-608 

•  Peroxide  of  manganese     .            .            .            .  0*560 

Carbonate  of  lime       .....  1-063 

Carbonate  of  magnesia     ....  1'688 

Potash  combined  with  silica               .            .            .  0*040 

Soda  combined  with  silica            .             .             .  0*012 

Phosphate  of  lime       .....  0035 

Sulphate  of  lime    .            .            .            .            .  a  trace 

Common  salt  .  .  .  .  .0  005 

Humus  soluble  in  alkalies            .            .             .  0-550 

Humus  with  several  azotized  organic  remains         .  1*333 

100*000 

Gypsum  acts  most  excellently  upon  this  land. 
The  soils  in  the  southern  range  of  the  Harz  moun- 
tains are  particularly  remarked  for  containing  more 
magnesia  than  lime.  Even  the  different  varieties 
of  marl  contain  a  considerable  quantity  of  magnesia. 
Thus  in  a  specimen  of  marl  obtained  from  the  vi- 
cinity of  Walkenried,  I  obtained  65J  per  cent,  car- 
bonate of  lime,  and  30^  per  cent,  carbonate  of  mag- 
nesia;  in  another  41  per  cent,  lime,  and  11  per  cent, 
magnesia;  and  in  a  third,  47|  per  cent,  lime,  and 
13J  per  cent,  magnesia.  Most  of  these  soils  contain 
also  J, —  1  per  cent,  of  gypsum,  and  |, —  1  per  cent, 
phosphate  of  lime,  and  are,  therefore,  well  fitted  for 
manuring  other  lands. 

19.  Subsoil  of  a  loam  from  a  depth  of  IJ  foot.  It 
occurs  in  the  vicinity  of  Brunswick.  The  surface- 
soil  is  remarkable  on  account  of  producing  beautiful 
red  clover  on  being  manured  with  gypsum ;  although 
the  soil  itself  contains  only  traces  of  lime,  magnesia, 
potash,  and  phosphoric  acid.  100  parts  of  the  sub- 
soil contained :  — 

Silica  and  coarse  siliceous  sand     .            .            .  88-980 

Alumina            .            .            .            .            .  2-240 

Protoxide  and  peroxide  of  iron      .            .            •  3-840 

Peroxide  of  manganese             .            ,            ,  a  trace 

Carbonate  of  lime                ....  2720 

Carbonate  of  magnesia              .            .             •  0*600 

Potash  and  soda      .....  0095 

20 


230 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Phosphate  of  lime 
Sulphate  of  lime 
Common  salt 


1-510 

a  trace 

0015 


100-000 

At  a  greater  depth  than  the  subsoil  of  which  the 
analysis  is  here  given,  the  soil  passes  into  marl, 
which  contains  20|  per  cent,  of  carbonate  of  lime. 
The  sulphuric  acid  deficient  in  the  soil  was  supplied 
by  means  of  the  gypsum. 


SOILS    IN    THE    KINGDOM    OF    HANOVER. 

20.  (A)  Analysis  of  a  barren  heath-soil  from 
Aurich  in  Ostfriesland ;  (B)  a  sandy  soil  containing 
much  humus  but  also  sterile;  (C)  a  sandy  soil 
possessing  the  same  characters  as  B.  100  parts 
contained :  — 


(A) 

(^ 

(C) 

Silica  and  coarse  siliceous  sand 

.  95-778 

85-973 

96  721 

Alumina 

0  320 

0-320 

0-370 

Protoxide  and  peroxide  of  iron 

.    0-400 

0440 

0-480 

Peroxide  of  manganese 

a  trace 

a  trace 

a  trace 

Lime 

.    0-286 

0160 

0005 

Magnesia 

0060 

0-240 

0080 

Soda        ..... 

.    0036 

0012 

0.036 

Potash         .         . 

a  trace 

a  trace 

a  trace 

Phosphoric  acid 

.  a  trace 

a  trace 

a  trace 

Sulphuric  acid    .... 

a  trace 

a  trace 

a  trace 

Chlorine  in  common  salt 

.    0052 

0-019 

0058 

Humus 

0768 

4-636 

0800 

Vegetable  remains 

.    2-300 

8-200 

1-450 

100-000    100-000    100000 
21.  Analysis    of  the    clayey    subsoil    of  a    moor, 
which,  after  being  burned,  is  used  as   a  manure  to 
the  above  soils  A,  B,  C.     100  parts  contain  :  — 

Silica  and  siliceous  sand            .            .            .  87*219 

Alumina        .            .            .            .            .        ,  4*200 

Peroxide  of  iron  with  a  little  phosphoric  acid   .  5.200 

Peroxide  of  manganese                  .            .            .  0-310 

Lime      ......  0-320 

Magnesia       ......  0380 

Potash  principally  combined  with  silica           .  0-130 

Soda  principally  combined  with  silica      .             .  0*274 
Sulphuric  acid  combined  with  lime,  magnesia,  and 

potash      .             .                        ...  0-965 

Chlorine             .....  0-002 

Humus       .            .            .            .            .            .  1000 

100-000 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  231 

By  comparing  this  analysis  with  that  of  the  three 
soils  which  have  preceded,  it  will  be  observed  that 
this  subsoil  is  fitted  to  impart  to  them  those  mineral 
ingredients  in  which  they  are  deficient. 

22,  Surface  soil  of  a  barren  heath  in  the  vicinity 
of  Walsrode  in  Luneberg.  100  parts  by  weight 
contain :  — 

Silica  and  siliceous  sand      ....  92*216 

Alumina  .....  0*266 

Peroxide  of  iron       .  •  .  .  .     0*942 

Protoxide  of  iron  ....  0*394 

Peroxide  of  manganese        ....  a  trace 

Lime,  in  combination  with  silica,  sulphuric  acid, 

and  humus      .....  1*653 

Magnesia,  in  combination  with  silica  .  .     0036 

Potash,  principally  in  combination  with  silica  0038 

Soda  .  .  .  .  .  .a  trace 

Phosphoric  acid  .  ...  .a  trace 

Sulphuric  acid  .....    0*051 

Chlorine  .  .  .  .  .a  trace 

Humus,  soluble  in  alkaline  carbonates       .  .    2  084 

Humus    ......  ]-900 

Resinous  matter       .....    0*420 


100000 

This  soil  contains  a  large  quantity  of  protoxide  of 
iron,  which,  together  with  a  deficiency  of  phosphoric 
acid,  is  the  cause  of  its  sterility.  But  when  this 
land  was  manured  with  the  ashes  of  peat,  it  was 
rendered  much  more  fertile.  The  ashes  used  for  this 
purpose  were  found  to  contain  in  100  parts  :  — 

Silica,  with  siliceous  sand  .  .  .    96*352 

Alumina  .....  1*859 

Peroxide  and  protoxide  of  iron,  with  a  little  phos- 
phoric acid  .....     1*120 

Peroxide  of  manganese  .  .  .  0*160 

Lime  .  .  .  .  .  .0*112 

Magnesia  .....  0*141 

Potash  ......    0-093 

Soda        ......  0007 

Sulphuric  acid  .      '      .  ,  .  .    0*152 

Chlorine  .....  0*004 


100000 

The  ashes,  on  exposure  to  the  air,  absorbed  am- 


monia. 


23.  Analysis  of  a  very  fertile  loamy  soil  from  Got- 
tingen.    It  is  very  rich  in  humus,  and  produces  beau- 


232 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


tiful   crops  of  peas,  beans,  lucern,  and  beet.     The 
sieve  separates  from  100  parts  of  the  soil :  — 

Small  stones,  principally  limestone  .  .         I 

Quartzy  sand,  with  a  little  magnetic  iron  sand   .  15 

Earthy  part     .  .  .  .  .  .84 


100 

100   parts  of  the   soil,  freed  from  stones,  consists 
of:  — 

Silica,  and  fine  siliceous  sand            .            .          .  83*298 

Alumina,  combined  with  silica              .             .  1 413 

Alumina,  partly  in  combination  with  humus  .  3'715 
Peroxide  and  protoxide  of  iron,  in   combination 

with  silica  .....  0*724 
Peroxide  and  protoxide  of  iron,  partly  free  and 

partly  in  combination  with  humus          .             .  2  244 

Peroxide  and  protoxide  of  manganese  .  0*280 
Lime,  with  coal  of  humus,  sulphur,  and  phosphoric 

acid            ......  1-814 

Magnesia,  combined  with  silica              .             .  0-422 

Magnesia,  combined  with  humus    .            •             .  0*400 

Potash     ......  0003 

Soda              .                         ....  0001 

Phosphoric  acid               ....  0166 

Sulphuric  acid          .            .            •            .            .  0-069 

Chlorine      ......  0-002 

Carbonic  acid  (as  carbonate  of  lime)           .            .  0440 

Humus,  soluble  in  alkalies         .             .             .  0789 

Humus,  with  a  little  water              .            .            .  3'250 

Nitrogenous  matter        .            .            .            .  0-960 

Resinous  matter       .  .  .  .  .a  trace 


100000 

The  subsoil  is  of  the  same  composition  as  the  sur- 
face, with  this  difference  only,  that  it  contains  more 
potash,  soda,  and  chlorine,*  and  is  interspersed  with 
fragments  of  fresh-water  shells.  Hence  it  is  that 
the  soil  produces  the  deep-rooted  plants  in  such  lux- 
uriance. 

24.  Soil  of  a  sterile  moor,  which  had  been  burned 
three  times,  and  upon  which  buckwheat  had  been 
cultivated.      100  parts  contained  :  — 

Humus,  soluble  in  alkalies  .  .  .     9-250 

Vegetable   remains,   charcoal,  quartzy  sand,  and 

earthy  particles     .  .  .  .  .  90-750 

100000 

*  The  portion  of  the  surface-soil  subjected  to  analysis  was  taken  from 
the  field  after  long-continued  rain.  Hence  the  small  quantity  of  salts 
of  potash  and  soda. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


233 


of 


100  parts  by  weight  left,  after  ignition,  10  parts 


ashes.      100  parts  of  these  ashes  consisted  of: 

Silica  and  siliceous  sand      ....  79*600 
Alumina 
Peroxide  of  iron 
Peroxide  of  manganese 


Carbonate  of  lime 

Carbonate  of  magnesia 

Potash 

Soda 

Phosphoric  acid 

Sulphate  of  lime  (gypsum) 

Chlorine 


6-288 
.    0-857 

0-400 
.    7-652 

1-640 
.    0080 

0-028 
.    0-215 

3235 
.    0-005 

100000 


Soils  such  as  this,  after  having  been  burned  seve- 
ral times,  and  made  to  produce  buckwheat,  are  com- 
pletely deprived  of  their  potash  and  soda ;  and  in 
consequence  of  this  are  rendered  quite  barren.  Hence 
it  is  that  ashes  of  wood  exert  such  an  astonishing 
effect  upon  them. 

25.  Analysis  of  a  very  fertile  loamy  sand,  from 
Osnabriick,  near  Rotherifeld.  It  is  remarkable  for 
being  manured  only  once  every  10  or  12  years,  and 
bears  beautiful  wheat  as  the  last  crop.  100  parts 
contain :  — 


Silica,  with  coarse  siliceous  sand    . 

• 

86-200 

Alumina              .... 

• 

2000 

Peroxide  and  protoxide  of  iron,  with  a  little 

phos- 

phoric  acid       .... 

, 

2-900 

Peroxide  of  manganese 

0100 

Carbonic  acid,  and  a  little  phosphate  of  lime 

, 

4-160 

Carbonate  of  magnesia 

0-520 

Potash  and  soda 

^ 

0035 

Phosphoric  acid        .... 

0-020 

Sulphuric  acid    .... 

• 

0021 

Chlorine       ..... 

0010 

Humus,  soluble  in  alkaline  carbonates 

, 

0  544 

Humus          ..... 

3-370 

Nitrogenous  matter 

. 

0-120 

100000 

The  soil  in  question  lies  on  the  southern  exposure 
of  a  hill,  which  consists  of  layers  of  limestone  and 
marl.  The  rain-water  penetrates  through  these  lay- 
ers, and  becomes  saturated  with  the  soluble  salts 
contained  in  them,  such  as  potash,  gypsum,  common 
salt,  lime,  magnesia,  and   saltpetre.     It   afterwards 

20* 


234  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

reaches  the  soil,  and  manures  it  with  these  ingredi- 
ents. It  is  only  in  this  manner  that  we  are  enabled 
to  explain  the  fertility  of  this  soil ;  for,  reasoning 
from  its  chemical  composition,  we  should  be  induced, 
a  priori,  to  suppose  that  it  would  be  barren.  At  the 
base  of  this  hill,  certain  portions  of  the  land  are 
covered  with  calcareous  tuff,  containing  the  above 
salts  :  a  fact  which  proves  that  the  water  which  pen- 
etrates through  the  soil  must  also  contain  them  in 
solution.  The  large  proportion  of  humus  exhibited 
by  the  analysis  depends  upon  the  nature  of  the  ma- 
nure with  which  it  was  treated. 

26.  Analysis  of  a  heavy  alluvial  soil,  from  Norden. 
100  parts  contain:  — 

Silica,  and  very  fine  siliceous  sand     .  ,  84*543 


Alumina 

Peroxide  of  iron 

Peroxide  of  manganese 

Lime 

Magnesia  . 

Potash  .... 

Soda,  in  combination  with  silica 

Phosphoric  acid,  in  combination  with  lime 

Sulphuric  acid  ... 

Chlorine  .  .  . 

Humus,  soluble  in  alkalies 


3-458 
3-488 
0-560 
0-319 
0-740 
a  trace 
6-004 
0-260 
0-008 
0-008 
0-416 


Hutnus  and  nitrogenous  matter  .  .  0-196 

100000 

The  portion  of  the  soil  subjected  to  analysis  was 
taken  at  a  depth  of  10  inches,  from  a  field  which 
had  received  no  manure  for  several  years.  It  had 
previously  produced  in  succession  barley,  beans, 
wheat,  and  grass,  the  latter  for  two  years.  The  soil 
is  remarkable,  in  a  chemical  point  of  view,  from  the 
large  quantity  of  soda  which  it  contains.  Although 
the  sulphuric  acid,  chlorine,  and  potash,  are  present 
in  small  quantity,  yet  this  does  not  present  any  bar- 
rier to  the  development  of  the  plants,  as  the  surface- 
soil  is  18  inches  in  depth. 

27.  Analysis  of  a  heavy  alluvial  soil  in  the  vicinity 
of  Norden.     100  parts  contain;  — 

Silica,  and  very  fine  siliceous  sand      .  .  79*174 

Alumina  .....      3016 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


235 


Peroxide  of  iron            .            . 

4-960 

Peroxide  of  manganese 

.      0-600 

Carbonate  of  lime 

2-171 

Carbonate  of  magnesia 

.      2226 

Potash,  in  combination  with  silica 

0025 

Soda,  idem 

.      6-349 

Phosphoric  acid 

0-534 

Sulphuric  acid        .             .             ,             , 

.    a  trace 

Chlorine             .... 

0005 

Humus,  soluble  in  alkalies 

.      0-782 

Humus,  with  nitrogenous  matter 

0-158 

100.000 

The  specimen  for  analysis  was  taken  at  a  depth 
of  10  inches  from  the  surface  of  a  field,  which  had 
been  manured  five  years  previously,  and  had  pro- 
duced since  that  time  rape,  rye,  wheat,  and  beans. 
The  crops  of  all  these  were  plentiful,  and  of  excel- 
lent quality.  It  is  singular  that  this  soil,  which 
contains  such  a  small  proportion  of  gypsum,  should 
be  adapted  for  the  cultivation  of  beans,  and  must 
be  ascribed  to  the  depth  of  the  surface-soil.  Yet, 
notwithstanding  this,  gypsum  would  form  a  beneficial 
manure  to  the  land. 

28.  Analysis  of  very  fertile  alluvial*  soil,  from 
Honigpolder;  no  manure  had  ever  been  applied  to 
it.     100  parts  contain:  — 

Siliceous  sand  separated  by  the  sieve     .  .  4*5 

Earthy  portion  of  the  soil 


100  parts  of  the  latter  consisted  of:  — 

Silica,  and  fine  siliceous  sand 

Alumina  .... 

Peroxide  of  iron  .... 

Peroxide  of  manganese 

Lime  .  .  •  .  . 

Magnesia  .... 

Potash,  principally  in  combination  with  silica 

Soda,  idem  .  .  . 

Phosphoric  acid  combined  with  lime  . 

Sulphuric  acid,  idem 

Chlorine  (in  common  salt)        .  .  . 

Carbonic  acid,  combined  with  lime 

Humus  soluble  in  alkalies 

Humus  .... 

Nitrogenous  matter      .... 

Water         ..... 


95-5 
1000 


64-800 
5.700 
6-100 
0090 
5-880 
0-840 
0-210 
0393 
0-430 
0-210 
0-201 
3-920 
2-540 
5-600 
1-582 
1504 


100000 


236 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Corn  has  been  cultivated  for  seventy  years  upon 
this  soil,  v^hich  has  never  received  dung  or  any  other 
kind  of  manure;  it  is,  how^ever,  occasionally  fallowed. 
The  subsoil  retains  the  same  composition  as  the 
surface-soil  for  a  depth  of  6-12  feet,  so  that  it  may 
be  considered  inexhaustible.  When  one  portion  of 
the  soil  is  rendered  unfit  for  use,  the  inferior  layers 
are  brought  up  to  the  surface. 

29.  Analysis  of  a  soil  from  Rahdingen,  near  Balje. 
In  this  case  the  sea  has  assisted  in  the  formation  of 
the  soil.  The  field  yielded  beautiful  corn  after  being 
manured  with  stable  dung,  being  particularly  re- 
marked for  its  fine  crops  of  v^heat,  beans,  and  winter 
barley.     100  parts  contain:  — 


Silica,  siliceous  sand,  and  silicates 

Alumina 

Peroxide  of  iron 

Peroxide  of  manganese 

Lime  .  .  .  • 

Magnesia 

Potash  and  soda  soluble  in  water 

Phosphoric  acid 

Sulphuric  acid 

Chlorine  (in  common  salt) 

Humus,  soluble  in  alkaline  carbonates 

Humus 

Nitrogenous  matter 

Water 


87012 
4-941 
2-430 
0192 
0-292 
0145 
0-005 
0114 
0074 
0003 
0-658 
2-668 
1-412 
0042 


100-000 

30.  Soil  of  a  field  remarkable  for  producing  large 
crops  of  hemp  and  horse-radish.  100  parts  con- 
sisted of:  — 


Silica  and  siliceous  sand 

Alumina 

Peroxide  of  iron 

Peroxide  of  manganese 

Lime 

Magnesia 

Potash 

Soda 

Phosphoric  acid  • 

Sulphuric  acid 

Chlorine 

Humus,  soluble  in  alkaline  carbonates 

Humus  and  nitrogenous  matter    . 


84-021 
4-498 
5120 
2-080 
0942 
1-740 
0-050 
0-012 
0-482 
0012 
0-008 
0-897 
0138 


100000 


I 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


237 


31.  Surface-soil  of  a  field  near  Drackenburg ;  it 
produces  very  bad  red  clover.    100  parts  contain:  — 

Silica,  with  very  fine  siliceous  sand          .  .    92-014 

Alumina            .            .            .             •            .  2*652 
Peroxide  of  iron                 ....      3*192 

Peroxide  of  manganese            .            .            .  0-480 

Lime          .            .            .            •            .  .      0*243 

Magnesia          .....  0-700 

Potash  combined  with  silica          .            .  .0*125 

Soda,  idem        .....  0-026 

Phosphoric  acid,  in  combination  with  lime  .      0*078 

Sulphuric  acid              ....  a  trace 

Chlorine                 .            .            .            .  .a  trace 

Humus  and  nitrogenous  matter            .  0*150 

Humus,  soluble  in  alkaline  carbonates     .  .      0*340  • 

100-000 

The  cause  that  clover  will  not  flourish  on  this  soil 
is  probably  due  to  the  deficiency  of  gypsum  and 
common  salt. 

32.  Surface-soil  of  a  field  near  Paddingbuttel. 
This  field  is  particularly  adapted  for  the  growth  of 
red  clover.     100  parts  consist  of:  — 


Silica  and  siliceous  sand 

Alumina  .... 

Peroxide  of  iron 

Peroxide  of  manganese 

Lime  ..... 

Magnesia  .... 

Potash,  principally  in  combination  with  silica 

Soda,  idem        .... 

Phosphoric  acid      .  .  .  . 

Sulphuric  acid  .  ... 

Chlorine  (in  common  salt) 

Humus,  soluble  in  alkaline  carbonates 

Humus,  with  nitrogenous  matter 


93-720 
1*740 
2-060 
0*320 
0121 
0*700 
0062 
0-109 
0103 
0005 
0050 
0*890 
0-120 

100-000 


SOILS    IN    BOHEMIA. 


33.  Surface-soil  of  a  very  fertile  field  in  the  prov- 
ince of  Dobrawitz  and  Lautschin.     100  parts  gave 


Siliceous  sand,  with  much  maffnetic  iron  sand 
Earthy  part  separated  by  the  sieve 


4-286 
95714 

100-000 


238 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


An  aqueous  infusion  of  the  soil  contained  gypsum, 
common  salt,  magnesia,  and  humus.  100  parts  of 
the  soil  gave  :  — 


Silica  .  .  , 

Alumina 

Protoxide  and  peroxide  of  iron 

Peroxide  of  manganese 

Lime 

Magnesia 

Potash,  in  combination  with  silica 

Soda,  idem  (principally)     . 

Phosphoric  acid,  in  combination  with  lime 

Sulphuric  acid,  idem 

Chlorine  (in  common  salt) 

Humus,  soluble  in  alkalies 

Humus 

Nitrogenous  matter 


89-175 
2-652 
3-136 
0-320 
1-200 
1-040 
0-075 
0354 
0-377 
0081 
0066 
0-920 
0-456 
0-208 

100000 


34.  Surface-soil  of  a  very  fertile  field  in  the  prov- 
ince of  Dobrawitz  and  Lautschin.  100  parts  of  the 
earth  consisted  of:  — 

Siliceous  sand,  with  a  little  magnetic  iron  sand  .    43-780 
Finer  part  separated  by  the  sieve  .         .        56-220 

100000 

100  parts  yielded  to  water  0*175  part  of  salts, 
consisting  of  common  salt,  gypsum,  magnesia,  and 
humic  acid.  100  parts,  by  weight,  of  the  earth  con- 
sisted of:  — 


loiiica  .  .  •  •  * 

Alumina  .... 

Protoxide  and  peroxide  of  iron 

Peroxide  of  manganese  . 

Lime  .  .  .  .  . 

Magnesia  .... 

Potash,  in  combination  with  silica 

Soda,  idem,  .... 

Phosphoric  acid,  in  combination  with  lime 

Sulphuric  acid,  idem 

Chlorine  (in  common  salt) 

Humus,  soluble  in  alkalies 

Humus  .  .  .  .  . 

Nitrogenous  matter 


.  89.634 

3224 
.    2-944 

1-160 
.    0-349 

0-300 
.    0-160 

0-428 
.    0-246 

0-005 
.    0-012 

0-750 
.    0-340 

0-448 

100-000 


35.  Analysis  of  a  soil  formed  by  the  disintegration 
of  basalt.     100  parts  of  the  earth  consisted  of:  — 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


239 


Siliceous  sand,  with  very  much  magnetic  iron  sand    8*428 
Earthy  portion  of  the  soil     ....  91-572 

100000 

The  aqueous  infusion  of  the  earth  contained  only 
traces  of  common  salt  and  gypsum,  with  humus, 
lime,  and  magnesia.     100  parts  consisted  of:  — 


Silica           ..... 

.    83-642 

Alumina            ..... 

3-978 

Protoxide  and  peroxide  of  iron 

.      5-312 

Peroxide  of  manganese 

0-960 

Lime           ..... 

.      1-976 

Magnesia           ..... 

0-650 

Potash,  in  combination  with  silica 

.      0080 

Soda,  idem         ..... 

0145 

Phosphoric  acid,  in  combination  with  lime 

.      0273 

Sulphuric  acid,  idem           .             .             .       . 

a  trace 

Humus,  soluble  in  alkaline  carbonates  . 

.      1-270 

Chlorine      .            .            .            .            .      . 

a  trace 

Humus,           ..... 

.      0234 

Nitrogenous  matter       .... 

1-480 

100  000 


Manure  consisting  of  gypsum,  common  salt,  or 
ashes  of  wood,  would  be  highly  conducive  to  the 
fertility  of  this  land. 


SOILS    IN    THE    "  MARKGRAFSCHAFT    MAHREN." 

36.  Surface-soil  of  a  field  very  remarkable  for  its 
fertility.  The  field  is  called  Haargraben,  and  is 
situated  near  the  village  of  Nebstein.  It  has  never 
been  manured  or  allowed  to  lie  fallow  and  yet  has 
produced  for  the  last  160  years  the  most  beautiful 
crops ;  thus  furnishing  a  remarkable  example  of  un- 
impaired fertility.  100*000  parts  of  this  soil  con- 
sisted of:  — 


Coarse  and  fine  siliceous  sand,  with  a  little  mag- 
netic iron  sand     .... 
Earthy  matter    ..... 


35-400 
64  600 

100  000 


100  parts  of  the  earth  yielded  to  water  0*010  sul- 
phuric acid,  0-010  chlorine,  0-007  soda,  0-012  mag- 
nesia, 0-010  potash,  with  a  little  silica,  humus,  and 


240  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

nitrogenous  matter,  but  no  appreciable  trace  of 
trates.     100  parts  of  the  soil  contained:  — 


Silica 

Alumina 

Peroxide  of  iron 

Peroxide  of  manganese 

Lime 

Magnesia 

Potash,  principally  in  combination  with  silica 

Soda,  idem 

Phosphoric  acid,  combined  with  lime  and  iron 

Sulphuric  acid,  combined  with  lime 

Chlorine  (in  common  salt) 

Humus,  soluble  in  alkalies 

Humus        .... 

Nitrogenous  matter 


77-209 
8-514 
6-592 
1-520 
0-927 
1-160 
0-140 
0640 
6-651 
0-011 
0-010 
0-978 
0-540 
1108 

100-000 


ni- 


It  is  apparent  from  the  above  analysis  that,  not- 
withstanding the  long  period  during  which  this  land 
h^s  been  cultivated  without  manure,  it  still  remains 
very  rich  in  matters  adapted  for  the  nutrition  of 
plants. 


SOILS    IN    HUNGARY. 


37.  Analysis  of  a  very  fertile  soil  from  Esakang. 
100  parts  of  the  earth  contained  :  — 


Very  fine  siliceous  sand 
Earthy  matter 


.    2-820 
97-180 

100  000 


The  aqueous  decoction  of  the  soil  contained  princi- 
pally gypsum,   common   salt,   silica,   magnesia,  and 


humus.     100  parts  of  the  soil  yielded  :  — 

Silica  .... 

Alumina 

Peroxide  and  protoxide  of  iron 

Peroxide  of  manganese 

Carbonate  of  lime 

Carbonate  of  magnesia 

Potash,  combined  with  silica         • 

Soda,  combined  with  silica 

Phosphoric  acid,  combined  with  lime 

Sulphuric  acid 

Chlorine  in  common  salt   .  • 


76-038 
4-654 
6112 
0-900 
3771 
4-066 
0-030 
1-379 
0-546 
0021 
0015 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


241 


Humus,  soluble  in  alkalies 

Humus 

Nitrogenous  organic  matter 


1-160 
1100 
0-208 

100000 


Subsoil  of  the  same  field  at  a  depth  of  two  feet. 
100  parts  consist  of: — ■ 

Very  fine  siliceous  sand  with  scales  of  mica  2-408 

Earth  separated  by  the  sieve     .  .  ,        97-592 


h 

100-000 

100  parts  of  the  earth  contain  :  — 

Silica          ..... 

.    59-581 

Alumina            .... 

3-224 

Peroxide  and  protoxide  of  iron 

.      4-896 

Peroxide  of  manganese 

0-720 

Carbonate  of  lime               .             , 

.     17-953 

Carbonate  of  magnesia 

11-075 

Potash,  combined  with  silica 

.      0-150 

Soda,  principally  combined  with  silica 

0-891 

Phosphoric  acid,  combined  with  lime 

.      0  846 

Sulphuric  acid,  idem     .             .             .             . 

0-004 
.      0'(m 

Chlorine  in  common  salt 

Humus,  soluble  in  alkalies 

0-536 

Humus,  with  nitrogenous  organic  matter  . 

.      0-120 

100-ooa 


BELGIUM. 


38.  Surface-soil  of  a  field  distinguished  for  its  fer- 
tility. It  had  received  no  manure  for  twelve  years  pre- 
vious to  the  time  at  which  the  analysis  was  executed. 
The  rotation  of  crops  for  the  latter  nine  years  was  as 
follows  :  —  1.  beans,  2.  barley,  3.  potatoes,  4.  winter 
barley  with  red  clover,  5.  clover,  6.  winter  barley, 
7.  wheat,  8.  oats ;  during  the  ninth  year  it  was 
allowed  to  lie  fallow.  The  soil  is  more  clayey  than 
loamy,  and  of  a  very  fine  grain.  Water  extracted 
from  the  soil,  0-013  soda,  0*002  lime,  0-012  magnesia, 
0-009  sulphuric  acid,  0-003  potash,  0-003  chlorine, 
with  traces  of  silica  and  humus.  100  parts  con- 
tained :  — 


Silica 

Alumina 

Peroxide  and  protoxide  of  iron 

Peroxide  of  manganese 

Carbonate  of  lime 

21 


64-517 
4810 
8316 
0  800 
9-403 


242 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Carbonate  of  magnesia 

Potash,  principally  combined  with  silica 

Soda  .  .  .  . 

Phosphoric  acid 

Sulphuric  acid  .  . 

Chlorine  .  .  . 

Humus  .... 


10-361 
0100 
0013 
1-221 
0009 
0  003 
0-447 

100-000 


ENGLAND. 


39.  Surface-soil  of  a  very  fertile  sandy  field  from 
the  vicinity  of  Tunbridge,  Kent,  according  to  Davy. 
100  parts  consisted  of:  — 


Loose  stones  and  gravel 

•                        • 

.    13-250 

Sand  and  silica 

•                        • 

58-250 

Alumina 

•                        • 

.      3-250 

Beroxide  of  iron 

•                        • 

1-250 

Carbonate  of  lime 

•                        • 

.      4-750 

Carbonate  of  magnesia 

•                        • 

0-750 

Common  salt  and  extractive  matter 

.      0-750 

Gypsum 

•                        • 

0-500 

Matter  destructible  by  heat 

•                        • 

.      3-750 

Vegetable  fibre 

•                        • 

3-500 

Water 

•                        • 

.      5-000 

Loss 

•                        • 

5-000 

100-000 

The  great  Davy,  who  was  convinced  of  the  impor- 
tance of  the  inorganic  constituents  of  soils,  has 
omitted  to  detect  the  phosphoric  acid,  potash,  soda, 
and  manganese.  All  these  must  have  been  present 
in  the  soil,  for  we  are  informed  that  it  produced 
good  hops,  for  which  these  ingredients  are  indis- 
pensable. 

40.  A  good  turnip  soil  from  Holkham,  Norfolk, 
yielded  to  Davy :  — 


Siliceous  sand 

Silica 

Alumina 

Peroxide  of  iron 

Carbonate  of  lime 

Vegetable  and  saline  matter 

Moisture  .        ~  . 


88-888 
1-666 
1222 
0-334 
7-000 
0556 
0-334 


100000 


t 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  243 


In  this  case  also,  phosphoric  acid,  manganese, 
potash,  magnesia,  &c.,  have  escaped  detection  by 
this  acute  chemist;  yet  doubtless  they  must  be 
present  in  the  soil,  for  we  are  informed  that  it  pro- 
duces good  turnips. 

41.  An  excellent  wheat  soil  from  the  neighborhood 
of  West  Drayton,  Middlesex,  according  to  Davy. 
100  parts  contained:  — 

Sand  and  silica                  ....  72*800 

Alumina          .....  11-600 

Carbonate  of  lime            ....  11-200 

Humus  and  moisture              .            .            .  4*400 


100*000 

This  analysis  has  been  executed  so  imperfectly, 
that  it  only  conveys  a  very  feeble  representation  of 
the  nature  of  the  soil.  A  soil  which  bears  good 
wheat  must  contain  phosphate  of  potash,  soda,  chlo- 
rine, and  sulphuric  acid ;  yet  none  of  these  are  exhib- 
ited by  the  analysis. 

42.  Surface-soil  of  a  fertile  field  in  the  neighbor- 
hood of  Bristol.     100  parts  contained  :  — 

Silica  and  siliceous  sand           .            .            .  60*000 

Alumina                  .....  12000 

Peroxide  of  iron            .            ,            .            .  3*500 

Lime  (carbonate)                .            .            .            .  7*500 

Magnesia           .....  0*500 

Humus        ......  1*250 

Saline  and  extractive  matter                .            .  0*750 

Water         ......  14*500 


100000 

Davy  has  made  several  analyses  of  various  fertile 
soils,  and  since  his  time  numerous  other  analyses 
have  been  published ;  but  they  are  all  so  superficial, 
and  in  most  cases  so  inaccurate,  that  we  possess  no 
means  of  ascertaining  the  composition  or  nature  of 
English  arable  land. 


SWEDEN. 


43.  Surface-soil  of  a  field  which  produces  the  most 
abundant  crops,  and  has  never  been  manured.  (Ber- 
zelius.)     100  parts  consist  of:  — 


244 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


Siliceous  sand  .... 

Silica  ..... 

Alumina  ..... 

Phosphates  of  lime  and  iron 

Carbonate  of  lime         .... 

Carbonate  of  magnesia 

Insoluble  extractive  matter 

Insoluble  extractive  matter  destructible  by  heat 

Animal  matter  .... 

Resin  ..... 

Loss  ..... 


57900 
14-500 
2000 
6000 
IJIOO 
1-000 
1-250 
4-000 
1-600 
0250 
0400 


100-000 

This  great  chemist  has  strangely  omitted  to  detect 
in  the  soil  potash,  soda,  chlorine,  sulphuric  acid,  and 
manganese.  As  this  soil  is  eminent  for  its  fertility, 
there  cannot  be  the  slightest  doubt  that  all  these 
ingredients  must  have  existed  in  it  in  notable  quan- 
tity. 


ISLAND    OF   JAVA. 

44.  A  very  fine-grained  loamy  soil,  colored  yellow 
by  peroxide  of  iron,  consisted  of; 

Silica  and  siliceous  sand 

Alumina 

Peroxide  and  protoxide  of  iron 

Peroxide  of  manganese 

Lime  .... 

Magnesia 

Potash,  principally  in  combination  with  silica 

Soda,  idem 

Phosphoric  acid 

Sulphuric  acid 

Chlorine 

Humus 

Water,  with  carbonic  acid 

100-000 


• 

.    67-660 

13-572 

• 

.     10-560 

1-640 

• 

.      0-912 

0-570 

th  silica 

.       0030 

0-184 

, 

.      0-391 

0-038 

. 

.      0010 

0368 

• 

.      4065 

"WEST    INDIES    (pORTO    RICO). 

45.  Surface-soil  of  a  very  barren  field.     100  parts 
contained :  — 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  245 


Silica  and  siliceous  sand 

• 

•            • 

70-900 

Alumina 

•                        • 

• 

6-996 

Peroxide,  and  protoxide  of 

iron  (much 

magnetic 

iron  sand) 

•            • 

• 

6102 

Peroxide  of  manganese 

. 

0-200 

Lime 

•             • 

• 

2-218 

Magnesia 

• 

3-280 

Potash 

•            • 

• 

0-130 

Carbonate  of  soda 

, 

6-556 

Phosphoric  acid,  combined  with  lime 

• 

1-362 

Sulphuric  acid,  combined  with  lime 

0-149 

Chlorine  in  common  salt 

,            , 

• 

0067 

Humus,  soluble  in  alkalies 

, 

0  540 

Humus 

•            • 

• 

1-500 

100-000 


This  soil  is  improved  by  gypsum.  Its  sterility  is 
due  to  the  excessive  quantity  of  carbonate  of  soda 
which  is  present. 


NORTH    AMERICA. 

46.  Surface-soil  of  alluvial  land  in  Ohio,  remark- 
able for  its  great  fertility.    100  parts  consisted  of:  — 

Silica  and  fine  siliceous  sand         .  .  •     79-538 

Alumina            .....  7-306 
Peroxide  and  protoxide  of  iron  (much  magnetic 

iron  sand)                   ....  5-824 

Peroxide  of  manganese                  .            .            .  1-320   • 

Lime                  .....  0-619 

Magnesia                 .....  1024 

Potash,  principally  combined  with  silica          .  0-200 

Soda            .            •      .      -     .       ;             -      .  *    -  ^^24 
Phosphoric  acid,  combined  with  lime  and  oxide  of 

iron          ......  1-776 

Sulphuric  acid,  combined  with  lime    .            .  0-122 

Chlorine                  ....            .  0  036 

Humus,  soluble  in  alkalies       .            .            .  1-950 

Nitrogenous  organic  matter           .            .            .  0*236 

Wax  and  resinous  matter         .            .            .  0-025 


100000 


47.  (A.)  Surface-soil  of  a  mountainous  district  in 
the  neighborhood  of  Ohio.  (B.)  analysis  of  the 
subsoil.  This  soil  is  also  distinguished  for  its  great 
fertility.     100  parts  contain  :  — 

21* 


246 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 


(A) 

(B) 

.  87143 

94-261 

5-666 

1-376 

.   2220 

2-336 

0-360 

1-200 

.   0-564 

0  243 

0-312 

0-310 

a  .   0 120  ) 
0-025  5 

0-240 

.   0-060 

a  trace 

0-0-27 

0034 

0036 

a  trace 

1-304 

.   1072 

0-080 

1011 

100-000 

100-000 

Silica  with  fine  siliceous  sand 

Alumina 

Peroxide  and  protoxide  of  iron 

Peroxide  of  manganese    . 

Lime  .... 

Magnesia 

Potash,  principally  combined  with  silica 

Soda         .... 

Phosphoric  acid         ... 

Sulphuric  acid     . 

Chlorine        •  .  .  . 

Humus,  soluble  in  alkalies 

Humus  .... 

Carbonic  acid,  combined  with  lime 

Nitrogenous  organic  matter 


In  the  preceding  part  of  the  chapter  we  have  in- 
serted a  number  of  analyses  of  various  soils,  as  well 
as  the  conclusions  deduced  from  them,  by  means  of 
which  the  farmer  may  be  enabled  to  ascertain  the 
manures  best  adapted  for  each  variety  of  soil.  By 
inspecting  the  analyses  of  the  sterile  soils,  it  will  be 
apparent  that  it  is  in  the  power  of  chemistry  to  point 
out  the  causes  of  their  sterility.  The  general  cause 
which  conduces  to  the  sterility  of  soils  is  either  the 
absence  of  certain  constituents  indispensable  for  the 
growth  of  plants,  or   the  presence  of  others,  which 

*  Soil   from   Chelmsford,  Massachusetts,  on  the  Merrimack   river, 

which  has  produced  a  large  crop  of  wheat  for  20  years,  with  only  one 

failure,  analyzed  by  Dr.  Dana.    100  parts  contain  :  — 

Soluble  geine 3.9228 

Insoluble   "      .  .  .  .  .  2-6142 

Sulphate  of  lime     .....       -7060 
Phosphate  of  '*  .  .  .  .  -9082 

Silicates  (silica,  alumina,  iron  &c.)  .  .  91-8485 

No  trace  of  carbonate  of  lime,  or  of  alkaline  salts,  could  be  discovered. 
Soil  from  Maine,  analyzed  by  Dr.  Jackson,  has  produced  48  bushels 

of  wheat  per  acre. 

Water  .  .  .  .  .  .5-0 

Vegetable  matter  ....  17-5 

Silica  ......    54-2 

Alumina  .....  106 

Subphosphate  of  alumina      .  .  .  .3-0 

Peroxide  of  iron  ....  7-0 

Oxide  of  manganese  .  ....       1*0 

Carbonate  of  lime  .  .  .  .  TS 


99-8 
From  Hitchcock's  Final  Report^  p.  29. 


ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS.  247 

exert  an  injurious  or  poisonous  action.  The  analy- 
ses are  those  of  Dr.  Sprengel, —  a  chemist  who  has 
unceasingly  occupied  himself  for  the  last  twenty 
years  in  endeavoring  to  point  out  the  importance 
of  the  inorganic  ingredients  of  a  soil  for  the  develop- 
ment of  plants  cultivated  upon  it.  He  considers  as 
essential  all  the  inorganic  bodies  found  in  the  ashes 
of  plants.  Now,  although  we  cannot  coincide  with 
him  in  the  opinion,  that  iron  and  manganese  are  in- 
dispensable for  vegetable  life,  (for  these  bodies  are 
found  as  excrementitious  matter  only  in  the  bark, 
and  never  form  a  constituent  of  an  organ,)  yet  we 
gratefully  acknowledge  the  valuable  services  which 
he  has  rendered  to  agriculture,  by  furnishing  a  natu- 
ral explanation  of  the  action  of  ashes,  marl,  &c.,  in 
the  improvement  of  a  soil.  Sprengel  has  shown, 
that  these  mineral  manures  afford  to  a  soil  alka- 
lies, phosphates,  and  sulphates;  and  further,  that 
they  can  exert  a  notable  influence  only  on  those 
soils  in  which  they  are  absent  or  deficient.  In  a 
former  chapter  of  this  book  I  have  endeavored  to 
point  out  the  importance  of  considering  these  con- 
stituents as  intimately  connected  with  the  vital  pro- 
cesses of  the  vegetable  organism,  and  have  shown 
that  the  different  families  of  plants  contain  unequal 
quantities  of  inorganic  ingredients.  This  subject 
has  been  left  unexamined  by  Sprengel,  yet  it  is  one 
of  much  importance ;  for  the  application  of  manures 
must  be  regulated  by  the  composition  of  the  plants 
which  are  cultivated  on  any  particular  soil.  Still, 
the  composition  of  the  soil  must  always  be  kept  in 
view.  Thus  it  would  be  perfect  extravagance  to 
manure  certain  soils  with  marl,  ashes,  or  gypsum; 
whilst,  on  the  contrary,  these  compounds  would  pro- 
duce the  most  beneficial  results  on  other  lands. 

In  a  former  part  of  the  work,  the  principal  action 
of  gypsum  upon  vegetation  was  ascribed  to  the  de- 
composition and  fixation  of  the  carbonate  of  ammonia 
contained  in  rain-water ;  but  gypsum  exerts  a  two- 
fold action.     The  power  of  decomposing  carbonate 


248  ON  THE  CHEMICAL  CONSTITUENTS  OF  SOILS. 

of  ammonia,  and  of  fixing  the  ammonia,  is  not  pecu- 
liar to  gypsum,  but  is  shared  also  by  other  salts  of 
lime  (chloride  of  calcium,  for  example).  But  it  acts 
also  as  a  sulphate,  and  when  useful  as  such  cannot 
be  replaced  by  any  other  salt  of  lime  which  does  not 
contain  sulphuric  acid. 

Hence  gypsum  can  be  replaced  as  a  manure  only 
by  a  mixture  of  a  salt  of  lime  with  ammonia,  and  a 
salt  of  sulphuric  acid.  Sulphate  of  ammonia  can 
therefore  be  substituted  for  gypsum,  and  exerts  a 
more  *  rapid  and  effectual  action.  In  France,  sul- 
phuric acid  has  been  poured  upon  the  fields  after  the 
removal  of  the  crops,  and  has  been  found  to  form  a 
good  manure.  But  this  is  merely  a  process  for  form- 
ing gypsum  in  situ;  for  the  soils  upon  which  it  is 
applied  contain  much  lime,  which  enters  into  com- 
bination with  the  sulphuric  acid.  It  would  certainly 
be  much  more  advantageous  to  form  sulphate  of  am- 
monia by  adding  the  acid  to  putrefied  urine,  and  to 
apply  this  mixture  to  the  field. 


APPENDIX  TO  PART  I. 


EXPERIMENTS  AND  OBSERVATIONS  ON  THE  ACTION  OF  CHARCOAL 
FROM  WOOD  ON  VEGETATION. 

BY    EDWARD    LUCAS.* 

**  In  a  division  of  a  low  hothouse  in  the  botanical  garden 
at  Munich,  a  bed  was  set  apart  for  young  tropical  plants, 
but  instead  of  being  filled  with  tan,  as  is  usually  the  case, 
it  was  filled  with  the  powder  of  charcoal,  (a  material  which 
could  be  easily  procured,)  the  large  pieces  of  charcoal 
having  been  previously  separated  by  means  of  a  sieve. 
The  heat  was  conducted  by  means  of  a  tube  of  white  iron 
into  a  hollow  space  in  this  bed,  and  distributed  a  gentle 
warmth,  such  as  tan  communicates,  when  in  a  state  of  fer- 
mentation. The  plants  placed  in  this  bed  of  charcoal  quick- 
ly vegetated,  and  acquired  a  healthy  appearance.  Now,  as 
always  is  the  case  in  such  beds,  the  roots  of  many  of  the 
plants  penetrated  through  the  holes  in  the  bottom  of  the 
pots,  and  then  spread  themselves  out  ;  but  these  plants 
evidently  surpassed  in  vigor  and  general  luxuriance  plants 
grown  in  the  common  way,  —  for  example,  in  tan.  Several 
of  them,  of  which  I  shall  only  specify  the  beautiful  Thun- 
bergia  alata,  and  the  genus  Peireskicc,  throve  quite  aston- 
ishingly ;  the  blossoms  of  the  former  were  so  rich,  that  all 
who  saw  it  affirmed,  they  had  never  before  seen  such  a 
specimen.  It  produced  also  a  number  of  seeds  without 
any  artificial  aid,  while  in  most  cases  it  is  necessary  to  ap- 
ply the  pollen  by  the  hand.  The  Peireskice  grew  so  vigor- 
ously, that  the  P.  aculeata  produced  shoots  several  ells  in 
length,  and  the  P.  grandifolia  acquired  leaves  of  a  foot  in 
length.  These  facts,  as  well  as  the  quick  germination  of 
the  seeds  which  had  been  scattered  spontaneously,  and  the 
abundant  appearance  of  young  Filices,  naturally  attracted 
my  attention,  and  I  was  gradually  led  to  a  series  of  ex- 
periments, the  results  of  which  may  not  be  uninteresting  ; 

*  See  page  78. 


250  APPENDIX  TO  PART  I. 

for,  besides  being  of  practical  use  in  the  cultivation  of  most 
plants,  they  demonstrate  also  several  facts  of  importance 
to  physiology.  The  first  experiment  which  naturally  sug- 
gested itself,  was  to  mix  a  certain  proportion  of  charcoal 
with  the  earth  in  which  different  plants  grew,  and  to  in- 
crease its  quantity  according  as  the  advantage  of  the  meth- 
od was  perceived.  An  addition  of  |  charcoal,  for  exam- 
ple, to  vegetable  mould,  appeared  to  answer  excellently  for 
the  Gesneria  and  Gloxima,  and  also  for  the  tropical  Aroidece 
with  tuberous  roots.  The  first  two  soon  excited  the  atten- 
tion of  connoisseurs,  by  the  great  beauty  of  all  their  parts 
and  their  general  appearance.  They  surpassed  very  quick- 
ly those  cultivated  in  the  common  way,  both  in  the  thick- 
ness of  their  stems  and  dark  color  of  their  leaves  ;  their 
blossoms  were  beautiful,  and  their  vegetation  lasted  much 
longer  than  usual,  so  much  so,  that  in  the  middle  of  Novem- 
ber, when  other  plants  of  the  same  kinds  were  dead,  these 
were  quite  fresh  and  partly  in  bloom.  Aroidece  took  root 
very  rapidly,  and  their  leaves  surpassed  much  in  size  the 
leaves  of  those  not  so  treated  ;  the  species  which  are  reared 
as  ornamental  plants  on  account  of  the  beautiful  coloring 
of  their  leaves,  (I  mean,  such  as  the  Caladium  bicolor, 
Pidumy  Pcecile,  &c.,)  were  particularly  remarked  for  the 
liveliness  of  their  tints  ;  and  it  happened  here  also,  that 
the  period  of  their  vegetation  was  unusually  long.  A 
cactus  planted  in  a  mixture  of  equal  parts  of  charcoal  and 
earth  throve  progressively,  and  attained  double  its  former 
size  in  the  space  of  a  few  weeks.  The  use  of  the  charcoal 
was  very  advantageous  with  several  of  the  Bromeliacece 
and  LiliacecB,  with  the  Citrus  and  Begonia  also,  and  even 
with  the  Palmce.  The  same  advantage  was  found  in  the 
case  of  almost  all  those  plants  for  which  sand  is  used,  in 
order  to  keep  the  earth  porous,  when  charcoal  was  mixed 
with  the  soil  instead  of  sand  ;  the  vegetation  was  always 
rendered  stronger  and  more  vigorous. 

**  At  the  same  time  that  these  experiments  were  performed 
with  mixtures  of  charcoal  with  different  soils,  the  charcoal 
was  also  used  free  from  any  addition,  and  in  this  case  the 
best  results  were  obtained.  Cuts  of  plants  from  different 
genera  took  root  in  it  well  and  quickly  ;  I  mention  here 
only  the  Euphorbia  fastuosa  ^ndfulgens  which  took  root  in 
ten  days,  Pandanus  utilis  in  three  months,  P.  amaryllifolius, 
Chammdorea  elatior  in  four  weeks.  Piper  nigrum,  Begonia^ 
Ficus,  Cecropia,  Chiococca,  Buddleya,  Hakea,  Phyllanthus, 
Capparis,  Laurus,    Stifftia,  Jacquinia  Mimosa,    Cactus,   in 


ACTION  OF  CHARCOAL  ON  VEGETATION.  251 

from  eight  to  ten  days,  and  several  others,  amounting  to 
forty  species,  including  Ilex  and  many  others.  Leaves, 
and  pieces  of  leaves,  and  even  pedunculi^  or  petioles,  took 
root  and  in  part  budded  in  pure  charcoal.  Amongst  others 
we  may  mention  the  foliola  of  several  of  the  Cycadecz,  as 
having  taken  root,  as  also  did  parts  of  the  leaves  of  the 
Begonia  Telfairice,  and  Jacaranda  brasiliensis  ;  leaves  of  the 
Euphorbia  fastuosa,  Oxalis  Barrilieri,  Ficus,  Cyclamen, 
Polyanthes,  Mesembryanthemum  ;  also  the  delicate  leaves 
of  the  Lophospermum  and  Mariynia,  pieces  of  a  leaf  of  the 
Agave  americana  ;  tufts  of  Pinus,  &c.  ;  and  all  without  the 
aid  of  a  previously  formed  bud.* 

**Pure  charcoal  acts  excellently  as  a  means  of  curing 
unhealthy  plants.  A  Dorianthes  excelsaj  for  example,  which 
had  been  drooping  for  three  years,  was  rendered  com- 
pletely healthy  in  a  very  short  time  by  this  means.  An 
orange  tree  which  had  the  very  common  disease  in  which 
the  leaves  become  yellow,  acquired  within  four  weeks  its 
healthy  green  color,  when  the  upper  surface  of  the  earth 
was  removed  from  the  pot  in  which  it  was  contained,  and  a 
ring  of  charcoal  of  an  inch  in  thickness  strewed  in  its 
place  around  the  periphery  of  the  pot.  The  same  was  the 
case  with  the  Gardenia. 

**I  should  be  led  too  far  were  I  to  state  all  the  results 
of  the  experiments  which  I  have  made  with  charcoal.  The 
object  of  this  paper  is  merely  to  show  the  general  effect 
exercised  by  this  substance  on  vegetation  ;  but  the  reader 
who  takes  particular  interest  in  the  subject  will  find  more 
extensive  observations  in  the  'Allgemeine  Deutsche  Garten- 
zeilung '  of  Otto  and  Dietrich,  in  Berlin  ;  or  Loudon's 
Gardener^ s  Magazine,  for  March,  1841. 

*'The  charcoal  employed  in  these  experiments  was  the 
dust-like  powder  of  charcoal  from  firs  and  pines,  such  as  is 
used  in  the  forges  of  blacksmiths,  and  may  be  easily  pro- 
cured in  any  quantity.  It  was  found  to  have  most  effect 
when  allowed  to  lie  during  the  winter  exposed  to  the  action 
of  the  air.  In  order  to  ascertain  the  effects  of  different 
kinds  of  charcoal,  experiments  were  also  made  upon  that 
obtained  from  the  hard  woods  and  peat,  and   also  upon 

*  The  cuttings  of  several  of  these  plants  being  full  of  moisture,  require 
to  be  partially  dried  before  they  are  placed  in  the  soil,  and  are  with 
difficulty  made  to  strike  root  in  the  usual  method.  The  charcoal  is 
probably  useful  from  its  absorbing  and  antiseptic  power.  The  Hakea 
is  extremely  difficult  to  propagate  from  cuttings.  All  the  Laurus  tribe 
are  obstinate,  some  of  them  have  not  rooted  under  three  years  from  the 
time  of  planting.  —  fF. 


252  APPENDIX  TO  PART  I. 

animal  charcoal,  although  I  foresaw  the  probability  that 
none  of  them  would  answer  so  well  as  that  of  pine  wood, 
both  on  account  of  its  porosity  and  the  ease  with  which  it 
is  decomposed.* 

'*It  is  superfluous  to  remark,  that  in  treating  plants  in 
the  manner  here  described,  they  must  be  plentifully  suppUed 
with  water,  since  the  air  having  such  free  access  penetrates 
and  dries  the  roots,  so  that  unless  this  precaution  is  taken 
the  failure  of  all  such  experiments  is  unavoidable. 

'*The  action  of  charcoal  consists  primarily  in  its  pre- 
serving the  parts  of  the  plants  with  which  it  is  in  contact, 
—  whether  they  be  roots,  branches,  leaves,  or  pieces  of 
leaves,  —  unchanged  in  their  vital  power  for  a  long  space 
of  time,  so  that  the  plant  obtains  time  to  develop  the  organs 
which  are  necessary  for  its  further  support  and  propaga- 
tion. There  can  scarcely  be  a  doubt  also  that  the  char- 
coal undergoes  decomposition  ;  for  after  being  used  five  to 
six  years  it  becomes  a  coaly  earth  ;  and  if  this  is  the  case, 
it  must  yield  carbon,  or  carbonic  oxide,  abundantly  to  the 
plants  growing  in  it,  and  thus  afford  the  principal  substance 
necessary  for  the  nutrition  of  vegetables.|  In  what  other 
manner,  indeed,  can  we  explain  the  deep  green  color  and 
great  luxuriance  of  the  leaves  and  every  part  of  the  plants, 
which  can  be  obtained  in  no  other  kind  of  soil,  according 
to  the  opinion  of  men  well  qualified  to  judge  ?  It  exercises 
likewise  a  favorable  influence  by  decomposing  and  absorb- 
ing the  matters  excreted  by  the  roots,  so  as  to  keep  the 
soil  free  from  the  putrefying  substances  which  are  often 
the  cause  of  the  death  of  the  spongiolce.  Its  porosity,  as 
well  as  the  power  which  it  possesses  of  absorbing  water 
with  rapidity,  and,  after  its  saturation,  of  allowing  all  other 
water  to  sink  through  it,  are  causes  also  of  its  favorable 
effects.  These  experiments  show  what  a  close  affinity  the 
component  parts  of  charcoal  have  to  all  plants,  for  every 
experiment   was    crowned   with   success,    although    plants 

*  M  Lucas  has  recently  repeated  these  experiments,  and  found  that 
the  animal  charcoal  obtained  by  the  calcination  of  bones  possesses  a 
decided  advantage  over  all  other  kinds  of  charcoal,  which  he  subjected 
to  expeiiment  —  Liebig's  Annalen^  Band  xxxix.  Heft  I.  5.  127. 

t  As  some  misconception  has  arisen  regarding  this  explanation  of  the 
action  of  charcoal  upon  vegetation,  and  an  idea  propagated,  that  the 
introduction  of  these  opinions  into  this  work  incorporated  them  with 
those  of  Liebig,  it  is  necessary  to  state  that  they  are  merely  inserted 
here  as  part  of  the  papers  of  M.  Lucas.  The  true  explanation  has 
been  given  in  a  former  part  of  the  work,  viz.  that  charcoal  possesses 
the  power  of  absorbing  carbonic  acid  and  ammonia  from  the  atmo- 
sphere, which  serve  for  the  nourishment  of  plants  —  Ed. 


ON  A  MODE  OF  MANURING  VINES.  253 

belonging  to  a  great  many  different  families  were  sub- 
jected to  trial."  [Buchner's  Repertorium,  ii.  Reihe,  xix. 
Bd.  S.  38.) 


ON   A   MODE    OF    MANURING   VINES. 

The  observations  contained  in  the  following  pages  should 
be  extensively  known,  because  they  furnish  a  remarkable 
proof  of  the  principles  which  have  been  stated  in  the  pre- 
ceding part  of  the  work,  both  as  to  the  manner  in  which 
manure  acts,  and  on  the  origin  of  the  carbon  and  nitrogen 
of  plants. 

They  prove  that  a  vineyard  may  be  retained  in  fertility 
without  the  application  of  animal  matters,  when  the  leaves 
and  branches  pruned  from  the  vines  are  cut  into  small 
pieces  and  used  as  manure.  According  to  the  first  of  the 
following  statements,  both  of  which  merit  complete  con- 
fidence, the  perfect  fruitfulness  of  a  vineyard  has  been 
maintained  in  this  manner  for  eight  years,  and  according 
to  the  second  statement  for  ten  years. 

Now,  during  this  long  period,  no  carbon  was  conveyed  to 
the  soil,  for  that  contained  in  the  pruned  branches  was  the 
produce  of  the  plant  itself,  so  that  the  vines  were  placed 
exactly  in  the  same  condition  as  trees  in  a  forest  which 
received  no  manure.  Under  ordinary  circumstances  a 
manure  containing  potash  must  be  used,  otherwise  the 
fertility  of  the  soil  will  decrease.  This  is  done  in  all  wine- 
countries,  so  that  alkalies  to  a  very  considerable  amount 
must  be  extracted  from  the  soil. 

When,  however,  the  method  of  manuring  now  to  be 
described  is  adopted,  the  quantity  of  alkalies  exported  in 
the  wine  does  not  exceed  that  which  the  progressive  dis- 
integration of  the  soil  every  year  renders  capable  of  being 
absorbed  by  the  plants.  On  the  Rhine  1  litre  of  wine  is 
calculated  as  the  yearly  produce  of  a  square  metre  of  land 
(10-8  square  feet  English).  Now  if  we  suppose  that  the 
wine  is  three-fourths  saturated  with  cream  of  tartar,  a  pro- 
portion much  above  the  truth,  then  we  remove  from  every 
square  metre  of  land  with  the  wine  only  1*8  gramme  of 
potash.  1000  grammes  (1  litre)  of  champagne  yield  only 
1*54,  and  the  same  quantity  of  Wachenheimer  172  of  a 
residue  which  after  being  heated  to  redness  is  found  to 
consist  of  carbonates. 

One  vine-stock,  on  an  average,  grows  on  every  square^ 
22 


254  APPENDIX  TO  PART  I. 

metre  of  land,  and  1000  parts  of  the  pruned  branches  con- 
tain 56  to  60  parts  of  carbonate,  or  38  to  40  parts  of  pure 
potash.  Hence  it  is  evident  that  4.5  grammes,  or  1  ounce, 
of  these  branches  contain  as  much  potash  as  1000  grammes 
(1  litre)  of  wine.  But  from  ten  to  twenty  times  this  quan- 
tity of  branches  are  yearly  taken  from  the  above  extent 
of  surface. 

In  the  vicinity  of  Johannisberg,  Rudesheim,  and  Budes- 
heim,  new  vines  are  not  planted  after  the  rooting  out  of  the 
old  stocks,  until  the  land  has  lain  for  five  or  six  years  in 
barley  and  esparsette  or  lucern ;  in  the  sixth  year  the 
young  stocks  are  planted,  but  not  manured  till  the  ninth. 


ON   THE    MANURING   OF    THE    SOIL    IN    VINEYARDS.^* 

**In  reference  to  an  article  in  your  paper.  No.  7,  1838, 
and  No.  29,  1839,  I  cannot  omit  the  opportunity  of  again 
calling  the  public  attention  to  the  fact,  that  nothing  more  is 
necessary  for  the  manure  of  a  vineyard  than  the  branches 
which  are  cut  from  the  vines  themselves. 

'*  My  vineyard  has  been  manured  in  this  way  for  eight 
years,  without  receiving  any  other  kind  of  manure,  and  yet 
more  beautiful  and  richly  laden  vines  could  scarcely  be 
pointed  out.  I  formerly  followed  the  method  usually  prac- 
tised in  this  district,  and  was  obliged  in  consequence  to 
purchase  manure  to  a  large  amount.  This  is  now  entirely 
saved,  and  my  land  is  in  excellent  condition.    • 

''When  I  see  the  fatiguing  labor  used  in  the  manuring 
of  vineyards, — horses  and  men  toiling  up  the  mountains 
with  unnecessary  materials,  —  I  feel  inclined  to  say  to  all, 
Come  to  my  vineyard  and  see  how  a  bountiful  Creator  has 
provided  that  vines  shall  manure  themselves,  like  the  trees 
in  a  forest,  and  even  better  than  they  !  The  foliage  falls 
from  trees  in  a  forest,  only  when  they  are  withered,  and 
they  lie  for  years  before  they  decay  ;  but  the  branches  are 
pruned  from  the  vine  in  the  end  of  July  or  beginning  of 
August  whilst  still  fresh  and  moist.  If  they  are  then  cut 
into  small  pieces  and  mixed  with  the  earth,  they  undergo 

*  Slightly  abridged  from  an  article  by  M.  Krebs  of  Seeheim,  in  the 
"  Zeitschrift  fur  die  landwirthschaftlichen  Vereine  des  Grosherzogthums 
Hessenr     No.  28,  July  9,  1840. 


I 


ON  THE  MANURING  OF  THE  SOH.  IN  VINEYARDS.  255 

putrefaction  so  completely,  that,  as  I  have  learned  by  ex- 
perience, at  the  end  of  four  weeks  not  the  smallest  trace 
of  them  can  be  found." 


"Remarks  of  the  Editor.  —  We  find  the  following 
notices  of  the  same  fact  in  Henderson's  *  Geschichte  der 
Weine  der  alien  und  neuen  Zeit '  :  — 

*'  *The  best  manure  for  vines  is  the  branches  pruned 
from  the  vines  themselves,  cut  into  small  pieces,  and  im- 
mediately mixed  with  the  soil.' 

"These  branches  were  used  as  manure  long  since  in  the 
Bergstrasse.     M.  Frauenfelder  says  :^ 

"  *  I  remember  that  twenty  years  ago,  a  man  called 
Peter  Miiller  had  a  vineyard  here,  which  he  manured  with 
the  branches  pruned  from  the  vines,  and  continued  this 
practice  for  thirty  years.  His  way  of  applying  them  was 
to  hoe  them  into  the  soil  after  having  cut  them  into  small 
pieces. 

"  '  His  vineyard  was  always  in  a  thriving  condition  ;  so 
much  so,  indeed,  that  the  peasants  here  speak  of  it  to  this 
day,  wondering  that  old  Miiller  had  so  good  a  vineyard, 
and  yet  used  no  manure.' 

"Lastly,  Wilhelm  Ruf  of  Schriesheim  writes  : 

"  'For  the  last  ten  years  I  have  been  unable  to  place 
dung  on  my  vineyard,  because  I  am  poor  and  can  buy 
none.  But  I  was  very  unwilling  to  allow  my  vines  to  de- 
cay, as  they  are  my  only  source  of  support  in  my  old  age; 
and  I  often  walked  very  anxiously  amongst  them,  without 
knowing  what  I  should  do.  At  last  my  necessities  became 
greater,  which  made  me  more  attentive,  so  that  I  remarked 
that  the  grass  was  longer  on  some  spots  where  the  branch- 
es of  the  vine  fell  than  on  those  on  which  there  were  none. 
So  I  thought  upon  the  matter,  and  then  said  to  myself:  If 
these  branches  can  make  the  grass  large,  strong,  and 
green,  they  must  also  be  able  to  make  my  plants  grow  bet- 
ter, and  become  strong  and  green.  I  dug  therefore  my 
vineyard  as  deep  as  if  I  would  put  dung  into  it,  and  cut  the 
branches  into  pieces,  placing  them  in  the  holes  and  cover- 
ing them  with  earth.  In  a  year  I  had  the  very  great  satis- 
faction to  see  my  barren  vineyard  become  quite  beautiful. 
This  plan  I  continued  every  year,  and  now  my  vines  grow 

*  Badisthes  landwirthschaftliches  IVochenblatt,  v.  1834,  S.  52  and  79. 


256  APPENDIX  TO  PART  I. 

Splendidly,  and  remain  the  whole  summer  green,  even  in 
the  greatest  heat. 

"  'AH  my  neighbors  wonder  very  much  how  my  vine- 
yard is  so  rich,  and  that  I  obtain  so  many  grapes  from  it, 
and  yet  they  all  know  that  1  have  put  no  dung  upon  it  for 
ten  years.'  ""^ 


ROOT    SECRETIONS. 

It  should  be  stated,  that  the  accuracy  of  the  experiments 
of  Macaire-Princep  adduced  by  the  author,  page  164,  is 
not  generally  admitted.  Other  chemists  have  been  unable 
to  obtain  similar  results,  or  if  they  do  are  inclined  to  as- 
cribe them  to  injury  of  the  roots  of  the  plants  examined. 
Professor  Lindley  in  his  notice  of  Liebig's  work  has  re- 
marked, that  he  has  no  fixed  opinion  on  the  subject,  it 
being  a  question  of  facts  and  not  of  induction.  Admitting 
root  secretions,  he  nevertheless  does  not  deem  it  necessary 
to  look  to  the  roots  for  these  excretions,  when  we  have  so 
many  proofs  of  their  constant  occurrence  in  other  parts  of 
a  plant,  as  in  the  oily,  resinous,  waxy,  acid,  and  acrid  mat- 
ter, from  various  parts  of  their  surface,  and  in  the  peculiar 
substances  lodged  in  the  hollows  of  their  stems  or  elsewhere, 
such  as  Tabasheer,  in  the  bamboo.  These  are  thought  to 
be  instances,  ''sufficient  to  satisfy  the  necessity  of  excre- 
tions occurring,  and  to  render  it  superfluous  to  look  to  the 
roots  for  further  aid  in  this  particular." 

The  subject  of  excretion  is  one  of  great  interest,  and 
deserving  of  further  examination.  Several  botanists  have 
recently  stated  what  are  deemed  fatal  objections  to  the  cor- 
rectness of  De  Candolle's  conclusions  from  Macaire's  ex- 
periments. It  is  maintained,  that  the  process  of  excretion 
from  the  roots  of  plants  is  not  analogous  to  that  of  excretion 
in  animals  ;  that  the  deposits  consist  of  materials  which 
were  in  superabundance  in  the  system  of  the  plant,  and 
that  the  reason  why  the  same  species  of  plants  do  not  grow 
one  after  the  other,  is,  that  the  first  exhausted  the  soil  of 
the  materials  necessary  for  the  nourishment  of  the  next. 
In  some  parts  of  the  world,  wheat  crops  are  said  to  have 
been  obtained  fifty  years  in  succession,  where  the  supply 
of  nutriment  was  sufficient.  The  application  of  the  recent 
discovery  of  the  means  of  coloring  the  wood  of  trees  by 

*  The  experiment  has  been  made  here  with  success  —  fV. 


ROOT  SECRETIONS.  257 

introducing  coloring  matters  into  their  trunks,  is  reported 
to  have  shown  that  the  coloring  matters  are  thrown  off 
from  the  roots,  and  plants  growing  near  them  have  been 
poisoned,  although  the  plant  colored  continued  to  grow. 
Report  of  British  Association  Meeting,  August,  1841. 

A  series  of  experiments  on  this  subject  has  been  going 
on  during  five  years  in  the  Botanic  Garden,  Oxford,  under 
the  direction  of  Professor  Daubeny.  His  object  is  to  as- 
certain, '*  in  the  first  place,  how  many  successive  years  the 
soil  may  admit  of  the  growth  of  the  same  crop,  and,  if  it 
becomes  deteriorated,  at  what  rate  the  decrease  of  produce 
may  proceed  ;  and,  in  the  second  place,  what  kind  of  vege- 
tables will  afterwards  thrive  best  in  soil,  which,  with  refer- 
ence to  this  particular  crop,  has  become  damaged,  or 
effete. 

"  With  a  view  to  determine  this,  I  have  set  apart,  in  one 
portion  of  our  Botanical  Garden,  a  number  of  distinct  plots 
of  ground,  of  known  size,  and  uniform  as  to  quality. 

*'  These  were  in  the  first  instance  enriched  with  an  equal 
amount  of  manure,  and  brought,  as  nearly  as  could  be 
done,  in  every  respect  into  a  similar  condition. 

'*  Fifteen  of  these  beds  are  planted  year  after  year,  with- 
out intermission,  with  the  following  crops  :  viz.  potatoes, 
turnips,  barley,  oats,  poppies  [Papaver  somniferum),  buck- 
wheat, tobacco  {JVicotiana  rustica),  flax,  hemp,  endive, 
clover  (Trifolium  pratense),  mint  {Mentha  viridis),  beans, 
parsley,  and  beet. 

•  "The  remaining  fifteen  beds  receive  in  turn  the  same 
crops,  but  each  year  a  different  one  is  introduced  ;  so  that 
by  comparing  the  amount  of  produce  obtained  each  year 
from  the  first  and  second  class  of  beds, — those  in  which 
the  crop  is  permanent,  and  those  in  which  it  is  made  to 
shift  about, — we  may  be  enabled  to  learn,  how  much  of 
any  actual  diminution  ought  to  be  attributed  to  the  season, 
and  how  much  to  a  deterioration  or  exhaustion  of  the  soil. 

**  As  it  is  scarcely  five  years  since  the  experiments  were 
commenced,  the  progress  made  has  not  yet  been  sufficient 
to  render  the  results  worth  quoting  ;  but  should  life  and 
leisure  be  allowed  me  for  bringing  them  to  a  conclusion, 
I  trust  some  inferences  may  hereafl«r  be  deduced  of  utility 
to  future  husbandmen  ;  although  I  should  be  far  more 
sanguine  with  respect  to  the  benefit  that  would  accrue,  if  a 
piece  of  ground  of  greater  extent  were  set  apart  for  such 
experiments,  as,  under  the  auspices  of  any  of  our  great 
Agricultural  Societies,  it  might  not  be  difliicult  to  efl^ect. 

22* 


258  APPENDIX  TO  PART  I. 

**  Should  Science,  indeed,  succeed  in  settling  the  true 
cause  of  the  deterioration  of  crops,  and  the  most  advan- 
tageous order  of  their  succession,  it  is  unnecessary  for  me 
to  point  out  how  important  a  boon  she  would  confer  upon 
the  agriculturist. 

*'So  extremely  various,  indeed,  are  the  systems  upon 
which  the  rotation  is  carried  on  in  different  countries,  that  ; 
no  fixed  principle  would  appear  to  regulate  them,  and  the  ' 
whole  may  be  considered,  as  being  founded  much  more 
upon  the  authority  of  long  usage  and  tradition,  than  upon 
any  actual  comparison  of  the  relative  advantages  of  those 
resorted  to  in  various  places. 

"This  inquiry  may  therefore  be  pointed  out,  as  being 
one  of  those  lines  of  investigation,  in  prosecuting  which 
the  scientific  chemist  may  be  expected  to  benefit  the  prac- 
tical farmer." 


PEAT    COMPOST. 
(Seep.  118,  and  185.) 

According  to  the  statement  of  Messrs.  Phinney  and 
Haggerston,  as  contained  in  the  Report  on  the  Geological  and 
Agricultural  Survey  of  Rhode  Island,  by  Dr.  C.  T.  Jack- 
son, a  compost  made  of  three  parts  of  peat  and  one  of  sta- 
ble manure,  is  equal  in  value  to  its  bulk  of  clean  stable 
dung,  and  is  more  permanent  in  its  eflTects. 

Dr.  Jackson  deems  it  essential  that  animal  matters  of 
some  kind  should  be  mixed  with  the  peat,  to  aid  the  de- 
composition and  produce  the  requisite  gases.  Lime  de- 
composes the  peat,  neutralizes  the  acids,  and  disengages 
the  ammonia.  The  peat  absorbs  the  ammonia,  and  be- 
comes in  part  soluble  in  water.  The  soluble  matter,  ac- 
cording to  Dr.  Jackson,  is  the  apocrenate  of  ammonia  ; 
crenate  of  ammonia  and  crenate  of  lime  being  also  dis- 
solved. With  an  excess  of  animal  matter  and  lime,  free 
carbonate  of  ammonia  is  formed. 

The  peat  should  be  laid  down  in  layers  with  barn-yard 
manure,  night-soil,  dead  fish,  or  any  other  animal  matter, 
and  then  each  layer  strewed  with  lime.  In  Dr.  Jackson's 
Report,  he  has  presented  highly  valuable  results  from  the 
use  of  this  compost,  which  deserve  the  attention  of  every 
agriculturist.     He  gives  the  following  details  of  the  man- 


PEAT  COMPOST.  259 

ner  in  which  the  compost  was  prepared  upon  the  farm  of 
Mr.  Sandford,  near  the  village  of  VVickford  in  North  King- 
ston. "  In  the  corner  of  the  field  a  cleared  and  level  spot 
was  rolled  down  smooth  and  hard,  and  the  swamp  muck 
was  spread  upon  it,  forming  a  bed  eight  feet  wide,  about 
fifteen  or  twenty  feet  long,  and  nine  inches  thick.  For 
every  wagon  load  of  the  muck  one  barrel  offish  was  added, 
and  the  fish  were  spread  on  the  surface  of  the  muck,  and 
allowed  to  become  putrescent.  The  moment  they  began  to 
decompose,  he  again  covered  them  with  peat,  and  a  renew- 
ed layer  of  fish  was  spread  and  covered  in  the  same  man- 
ner. The  fermentation  was  allowed  to  proceed  for  two  or 
three  weeks,  when  the  compost  was  found  to  have  become 
fit  for  the  land.  To  this  he  was  advised  to  add  lime  in  the 
proportion  of  one  cask  to  each  load  of  compost  early  in 
the  spring,  which  it  was  supposed  would  complete  the  de- 
composition in  two  or  three  weeks.  Such  a  heap  should 
be  rounded  up  and  covered,  so  as  to  prevent  the  rain  wash- 
ing out  the  valuable  salts,  that  form  in  it.  And  in  case  of 
the  escape  of  much  ammonia,  more  swamp  muck  or  peat 
should  be  spread  upon  the  heap,  for  the  purpose  of  absorb- 
ing it."  Dr.  Jackson  is  of  opinion,  that  the  phosphoric  acid 
of  the  peat  and  animal  matter  would  convert  the  lime  into 
a  phosphate,  and  thus  approximate  it  very  closely  to  bone 
manure. — Report,  p.  170. 

Any  refuse  animal  matter  can  be,  of  course,  employed 
in  a  similar  manner.  **  The  carcass  of  a  dead  horse,  which 
is  often  suffered  to  pollute  the  air  by  its  noxious  effluvia, 
has  been  happily  employed  in  decomposing  20  tons  of  peat 
earth,  and  transforming  it  into  the  most  enriching  manure." 
—  Young's  Letters  of  Jlgricola,  Letter  25,  p.  238.* 

Night  soil  may  be  composted  with  peat  with  great  advan- 
tage, sufficient  lime  being  added  to  deprive  it  of  odor;  large 
quantities  of  ammonia  are  given  off*  and  absorbed. t 

Appended  to  Dr.  Jackson's  Report  will  be  found  a  letter 

*  In  a  Report  on  a  Reexamination  of  the  Geology  of  Massachusetts, 
1838,  Dr.  Dana  particularly  notices  the  evolution  of  ammonia  from  fer- 
menting dung,  and  supposes  that  the  ammonia  combines  with  geine  to 
form  a  soluble  compound.     See  JVote  to  page  83  of  the  Report. 

f  Mght-SoiL  The  quantity  of  night-soil  collected  and  removed  from 
the  city  of  Boston  annually,  is  about  four  hundred  thousand  square  feet. 
It  is  used  by  cultivators  in  the  immediate  vicinity,  being  composted 
with  soil,  lime,  peat^  &c.  Large  quantities  of  animal  matter  from 
slaughter-houses,  and  other  sources,  are  also  made  use  of.  The  heaps 
are  left  exposed,  uncovered  to  the  air,  and  the  value  of  the  compost  is 
consequently  greatly  diminished.     See  page  199. 


260  APPENDIX  TO  PART  I.  < 

from  E.  Phinney,  Esq.,  of  Lexington,  well  known  as  one 
of  the  most  skilful  agriculturists, "On  the  reclaiming  of  peat 
bogs  and  the  employment  of  peat  as  manure." 


SOURCE  OF  THE  CARBON  OF  PLANTS.   (fROM  DAUBENY's 
LECTURES  ON  AGRICULTURE,  1841.) 

(See  Chapter  II.) 

**  Until  within  the  last  century,  it  would  have  been  taken 
for  granted,  that  the  soil  was  the  source  from  whence  pro- 
ceeded all  the  solid  matter  at  least  which  entered  into  the 
constitution  of  a  plant,  and  there  were  several  circumstan- 
ces which  tended  to  countenance  such  an  opinion.  No 
plants,  it  was  observed,  would  continue  long  to  thrive  in 
earth  unmixed  with  some  proportion  of  vegetable  mould, 
and  the  fertility  of  the  latter  is  greatly  enhanced  by  the 
addition  of  animal  or  vegetable  matter,  in  that  state  of  de- 
cay, in  which  it  becomes  soluble  in  water,  and  therefore 
fitted  to  obtain  admission  into  the  vessels  of  plants. 

"Hence,  when  Priestley  had  demonstrated,  that  leaves 
decompose  the  carbonic  acid  of  the  atmosphere,  giving  out 
its  oxygen  and  assimilating  its  carbon,  the  doctrine  alluded 
to  still  to  a  certain  extent  maintained  its  ground;  and  it  was 
even  questioned  by  Ellis  and  others,  whether  in  fact,  if  we 
were  to  strike  the  balance  between  the  opposite  influence 
of  a  plant  during  the  day  and  the  night,  as  much  carbonic 
acid  might  not  be  exhaled  by  it  at  one  period,  as  had  been 
decomposed  at  another. 

*'  I  was  therefore  induced  myself  to  undertake  some  ex- 
periments,* the  results  of  which  appear  to  establish,  that 
plants,  even  in  a  confined  atmosphere,  do  in  reality  add  a 
great  deal  more  oxygen  to  the  air  than  they  abstract  from 
it,  whilst  the  amount  of  carbonic  acid  which  may  be  intro- 
duced undergoes  at  the  same  time  a  corresponding  dimi- 
nution. 

''  This  effect  I  even  found  to  take  place  in  diffused  light, 
as  well  as  under  the  direct  influence  of  the  solar  rays,  and 
to  be  no  less  common  in  aquatic  than  in  terrestrial  plants. 

*'  I  also  showed,  that  when  a  branch  loaded  with  flowers, 
as  well  as  with  leaves,  was  introduced  into  a  jar  containing 

<*  *  See  Philosophical  Transactions  for  1836." 


DAUBENY  ON  THE  CARBON  OF  PLANTS.        261 

a  certain  proportion  of  carbonic  acid,  the  balance  still  con- 
tinued to  be  in  favor  of  the  purifying  influence  of  the  veg- 
etable. 

'*The  apparatus  I  made  use  of  consisted  of  a  large  bell- 
glass  jar,  containing  in  one  case  600,  in  another  800  cubic 
inches  of  air,*  and  suspended  by  pulleys.  Its  edges  dipped 
into  quicksilver,  contained  in  a  double  iron  cylinder  of  cor- 
responding dimensions  to  the  jar,  which,  being  closed  at 
bottom,  constituted  a  well  of  about  six  inches  in  depth,  cal- 
culated to  receive  a  fluid,  and  to  admit  of  the  glass  vessel 
moving  freely  in  it.  The  inner  margin  of  this  hollow  cylin- 
der was  cemented  air-tight,  according  as  circumstances  re- 
quired, either  to  a  plate  of  iron,  or  to  a  pot  of  the  same 
material  upon  or  in  which  the  plant  operated  on  might  be 
placed  ;  and  the  jar  was  then  let  down  upon  it,  until  its 
edges  were  sunk  a  little  beneath  the  surface  of  the  mercury. 

"Thus  all  communication  with  the  external  atmosphere 
'was  cut  oflf,  and  the  eflfect  of  the  plant  upon  the  air  inclosed 
in  the  jar  was  readily  measured,  by  simply  pressing  down 
the  latter,  and  thus  expelling  a  portion  of  its  contents 
through  a  tube,  communicating  with  its  interior,  and  intro- 
duced at  its  outer  extremity  under  a  pneumatic  trough, 
wherein  the  air  might  be  collected  and  examined.  By  con- 
necting this  extremity  with  a  vessel  containing  a  measured 
quantity  of  carbonic  acid,  and  raising  the  jar  a  little  in  the 
well  of  mercury,  it  was  easy  to  draw  in  any  proportion  of 
that  gas,  with  which  it  was  thought  proper  that  the  plant 
should  be  supplied.  A  portion  of  the  air  was  always  tested, 
immediately  after  the  introduction  of  every  fresh  portion 
of  carbonic  acid,  and  again  after  an  interval  of  some  hours, 
and  the  proportion  of  this  gas  and  of  oxygen  present  was 
each  time  carefully  registered.  The  amount  of  carbonic 
acid  was  determined  by  a  solution  of  potass,  that  of  oxygen 
by  the  rapid  combustion  of  phosphorus  with  a  portion  of  it 
introduced  into  a  bent  tube. 

''  Such  was  the  mode  of  procedure,  when  an  entire  plant 
became  the  subject  of  experiment  ;  but  some  of  the  most 
satisfactory  trials  were  with  branches  of  certain  shrubs, 
themselves  too  large  to  be  admitted  under  the  jar.  These 
branches,  without  being  detached  from  the  parent  trunk, 
were  introduced  through  a  hole  in  the  centre  of  two  corre- 
sponding semicircular  plates  of  iron,  which  were  cemented 
air-tight,  to  the  inner  margin  of  the   iron   cylinder  on  the 

**  *  Larger  jars,  containing  from  1200  to  1300  cubic  inches  were  lat- 
terly employed." 


262  APPENDIX  TO  PART  I. 

one  hand,  and  to  the  stem  of  the  branch  on  the  other.  In 
this  manner,  when  the  jar  came  to  be  placed  over  them, 
and  to  dip  beneath  the  surface  of  the  mercury,  the  external 
air  was  as  effectually  excluded,  as  when  the  whole  of  the 
plant  had  been  enclosed. 

^*The  results  of  several  experiments  conducted  after 
this  plan  are  given  in  a  tabular  form  in  the  Memoir  ;  but 
it  may  be  sufficient  here  to  specify  one  of  the  most  satis- 
factory of  those  undertaken.  In  this  case  the  jar  itself 
contained  about  600  cubic  inches  of  air,  and  the  plant  ex- 
perimented on  was  the  common  lilac  {syringa  vulgaris). 
The  proportion  of  carbonic  acid  in  the  jar  was  each  morn- 
ing made  equivalent  to  five  or  six  per  cent,  by  additions 
through  the  tube. 

*'The  first  day  no  great  alteration  in  the  air  was  detect- 
ed, but  on  the  second  day,  by  eight  in  the  evening,  the 
oxygen  had  risen  to  ^6'5  per  cent.  In  the  morning  it  had 
sunk  to  26  0,  but  by  two  P.  M.  it  had  again  risen  to  no  less 
than  29*75,  and  by  sunset  it  had  reached  30*0  per  cent.  At 
night  it  sunk  one  half  per  cent.  ;  but  the  efl^ect  during  the 
following  day  was  not  estimated,  as  the  sickly  appearance 
which  the  plant  now  began  to  assume  induced  me  to  sus- 
pend the  experiment. 

''In  a  second  trial,  however,  the  branch  of  a  healthy 
lilac  growing  in  the  garden  was  introduced  into  the  same 
jar,  where  it  was  suffered  to  remain  until  its  leaves  became 
entirely  withered. 

"The  first  day  the  increase  of  oxygen  in  the  jar  was  no 
more  than  025  per  cent.,  but  on  the  second  it  rose  to  25*0. 
At  night  it  sunk  to  nearly  22*0  per  cent.,  but  the  next 
evening  it  had  again  risen  to  27  0.  This  was  the  maximum 
of  its  increase,  for  at  night  it  sunk  to  26*0.  and  in  the 
morning  exhibited  signs  of  incipient  decay.  Accordingly 
in  the  evening  the  oxygen  amounted  only  to  26*5  ;  the 
next  evening  to  255  ;  the  following  one  to  24*75  ;  and  the 
one  next  succeeding  it  had  fallen  to  the  point  at  which  it 
stood  at  the  commencement,  or  to  21*0  per  cent. 

*'The  reason  of  this  decrease  was,  however,  very  mani- 
fest from  the  decay  and  falling  off*  of  the  leaves  ;  so  that 
this  circumstance  does  not  invalidate  the  conclusion  which 
the  preceding  experiments  concur  in  establishing,  namely, 
that  in  fine  weather  a  plant,  so  long  at  least  as  it  continues 
healthy,  adds  considerably  to  the  oxygen  of  the  air  when 
carbonic  acid  is  freely  supplied. 

*'  In  the  last  instance  quoted,  the  exposed  surface  of  all 


I 


DAUBENY  ON  THE  HYDROGEN  OF  PLANTS.  263 


the  leaves  enclosed  in  the  jar,  which  were  about  fifty  in 
number,  was  calculated  at  not  more  than  300  square  inches, 
and  yet  there  must  have  been  added  to  the  air  of  the  jar  as 
much  as  26  0  cubic  inches  of  oxygen,  in  consequence  of 
the  action  of  this  surface  upon  the  carbonic  acid  introduced. 

**  But  there  is  reason  to  believe,  that  even  under  the  cir- 
cumstances above  stated  (which  appear  more  favorable  to 
the  due  performance  of  the  functions  of  life  than  those  to 
which  Mr.  Ellis's  plants  were  subjected),  the  amount  of 
oxygen  evolved  was  much  smaller  than  it  would  have  been 
in  the  open  air,  for  I  have  succeeded,  by  introducing  sev- 
eral plants  into  the  same  jar  of  air  in  pretty  quick  succes- 
sion, in  raising  the  amount  of  oxygen  contained  from  twen- 
ty-one to  thirty-nine  per  cent.,  and  probably  had  not  even 
then  attained  the  limit  to  which  the  increase  of  this  con- 
stituent might  have  been  brought. 

'^  How  great  then  must  be  the  effect  of  an  entire  tree  in 
the  open  air  under  favorable  circumstances  !  and  we  must 
recollect  that,  cceteris  paribus^  the  circumstances  will  be 
favorable  to  the  exertion  of  the  vital  energies  of  the  plant, 
within  certain  limits  at  least,  in  proportion  as  animal  respi- 
ration and  animal  putrefaction  furnish  to  it  a  supply  of  car- 
bonic acid. 

*'  These  experiments  were  published  in  the  Philosophical 
Transactions  for  1836,  and  have  been  noticed  in  Dr.  Lind- 
ley's  popular  Introduction  to  Botany  ;  neither  am  I  aware 
that  the  deductions  which  were  drawn  from  them  have  any- 
where been  disputed." 

Source  of  the  Hydrogen  of  Plants;  from  Daubeny^s  Lectures, 

(See  Chapter  IV.) 

**It  would  seem,  I  think,  from  the  late  important  re- 
searches of  M.  Payen,  that  the  decomposition  of  water 
commences  subsequently  to  that  of  carbonic  acid,  whether 
it  be,  that  the  former  process  requires  a  greater  develop- 
ment and  energy  in  the  vegetable  functions,  or  that  it  takes 
place  in  organs  of  a  different  description  and  of  later 
growth. 

''M.  Payen  seems  to  have  established,  that  under  the 
general  term  of  ligneous  fibre,  or  lignin,  we  have  hitherto 
confounded  at  least  two  distinct  substances,  namely,  that 
which  constitutes  the  walls  of  the  cells,  and  that  which,  by 
being  deposited  afterwards  on  the  surfaces  of  the  latter, 


264 


APPENDIX  TO  PART  I. 


imparts  to  them  the  solidity  of  texture  which  woody  fibre 
possesses. 

'*He  has  succeeded  in  isolating  the  two  by  chemical 
means,  and  has  found,  that  whilst  the  cellular  matter  has 
exactly  the  same  composition  as  starch,  being  composed 
of  44*9  carbon,  6*1  hydrogen,  49  oxygen,  or  44*9  carbon 
and  55*1  of  water;  the  incrusting  matter  afterwards  formed 
consists  of  53 -76  carbon,  40.2  oxygen,  and  6  of  hydrogen, 
or  of  53*76  carbon,  45*2  of  water,  and  1  of  hydrogen.^ 

^*The  composition  of  the  ligneous  matter  of  different 
kinds  of  wood  will  therefore  vary  according  to  the  relative 
proportion  of  these  two  ingredients,  as  is  shown  in  the 
following  table  of  M.  Payen  :  — 


Ligneous  Bodies. 

Carbon. 

Hydrogen. 

Oxygen. 

Incrusting 

Incrusting  matter  of  the  wood 

matter. 

53-76 

6-00 

40-20 

100 

Wood  of  Saint  Lucia 

5290 

6-07 

4103 

90 

Ebony           .... 

52-85 

600 

41-15 

89 

Walnut     .... 

5192 

5-96 

4212 

82 

Oak 

50-00 

620 

43-80 

61 

Ditto   according  to  Gay-Lus- 

sac,  and  Th^nard 

51-45 

5-82 

42-73 

Beech        .... 

4925 

6-10 

44-65 

52 

Cellular  matter     . 

44-90 

6-10 

49  00 

00 

**This  then  proves,  that,  in  the  formation  of  the  matter 
which  incrusts  and  fortifies  the  walls  of  the  cellular  tissue 
in  wood,  though  not  in  that  of  the  cellular  tissue  itself,  a 
decomposition  of  water  must  have  taken  place  ;  since  the 
1  per  cent,  of  hydrogen  which  Payen  has  found  in  excess, 
can  only  have  arisen  in  this  manner. 

*'This  increase  of  hydrogen  becomes  still  greater,  when, 
in  the  progress  of  vegetation,  the  plant  begins  to  secrete 
oils,  camphors,  and  other  analogous  bodies,  products, 
which,  it  is  to  be  remarked,  abound  most  within  the  tropics, 
where  the  light  of  the  sun  is  most  intense. 

'*  Hence  the  decomposition  of  water,  no  less  than  that 
of  carbonic  acid,  seems  due  to  solar  influence,  and  accord- 
ingly, the  greater  sweetness  of  subacid  fruits,  in  a  warm 
than  in  a  cold  summer,  arises  from  the  transformation  of 
a  larger  amount  of  tartaric  or  other  vegetable  acids  into 
sugar,  owing  to  that  separation  of  oxygen  from  the  former 
which  is  accomplished  by  the  agency  of  light. 

*'The  process  of  assimilation  of  plants  in  its  most  simple 

"  *  Payen  has  since  stated,  that  this  incrusting  matter  probably  con- 
sists of  two  or  three  different  principles." 


DAUBENY  ON  THE  NITROGEN  OF  PLANTS.  265 

form  may  therefore  be  stated,  as  consisting  in  the  extrica- 
tion of  hydrogen  from  water,  and  of  carbon  from  carbonic 
acid,  in  consequence  of  which  one  of  three  things  must 
happen, — either  all  the  oxygen  of  the  water  and  of  the 
carbonic  acid  are  separated,  as  in  those  bodies  which,  like 
caoutchouc,  volatile  oils,  &c.,  consist  of  nothing  else  but 
carbon  and  hydrogen  ;  or,  secondly,  only  a  part  of  it  is 
exhaled,  as  in  the  case  of  the  incrusting  matter  of  wood, 
and  in  sugar  ;  or,  thirdly,  that  belonging  to  the  carbonic 
acid  alone  is  decomposed,  whilst  the  water  remains,  as  in 
starch  and  cellular  tissue." 


Dependence  of  the  nutritive  Qualities  of  Plants  on  their  jyitro^ 
gen;  from  Dauheny^s  Lectures. 

(See  page  139.) 

'*The  dependence  of  the  nutritive  qualities  of  various 
articles  of  food  upon  the  proportion  of  nitrogen  is  well 
shown  in  a  recent  memoir  of  Monsieur  Boussingault,*  who 
gives,  on  the  authority  of  the  celebrated  agriculturist  Von 
Thaer,  a  scale  of  the  relative  degree  of  nutriment  afforded 
by  various  plants  to  cattle,  and  then  places  by  the  side  of  it 
a  statement  of  the  proportion  of  azote  present  in  them,  from 
which  it  appears,  that  the  nutritious  quality  of  each  bears 
a  pretty  constant  ratio  to  the  quantity  of  nitrogen  they 
contain. 

"This  may  be  seen  by  the  following  table  : 

Equiv. 


Ordinary  hay 

100  its  azote  being  001 18 

Red  Clover 

.      90        .        .        .    00176 

Beans 

.        .          83    .        .        .        0-0141 

Wheat- straw 

.    400        .        .        .    00020 

Potatoes 

200     .        .        .        0-0037 

Beet 

.    397        .        .        .    0-0026 

Maize 

59    .        .        .        0-0164 

Barley 

.      54        .        .        .    0-0176 

Wheat      . 

27    .        .        .        0-0213 

'*When  we  reflect,  indeed,  that  animal  matter,  which  so 
abounds  in  nitrogen,  is  nevertheless  derived,  either  directly 
or  indirectly,  from  vegetable,  it  follows,  as  a  necessary 
consequence,  that  existence  can  only  be  maintained  by  the 
aid  of  those  principles  in  plants,  which  contain  a  certain 
proportion  of  the  element  alluded  to. 

"  *  Annales  de  Chimie,  Vol.  LXIII." 

23 


266  APPENDIX  TO  PART  I. 

**And  this  has  been  shown  by  the  experiments  of  Ma- 
gendie  upon  dogs,  which  were  fed  on  sugar,  starch,  gum, 
and  other  substances  destitute  of  nitrogen,  and  in  a  very 
short  time  pined  away  and  died." 

Difference  between  different  Plants  in  their  power  of  decom- 
posing Ammonia;  from  Daubeny^s  Lectures, 

(See  Chapter  V.) 

**It  maybe  inferred,  from  some  experiments  made  by 
Boussingault,  that  a  great  difference  exists  between  plants 
in  their  power  of  assimilating  nitrogen,  and  to  this  differ- 
ence that  chemist  is  disposed  to  attribute  the  advantage  of 
alternately  growing  what  are  called  fallow  crops,  for  the 
purpose  of  refreshing  the  soil. 

*' 'During  germination,'  he  remarks,  *the  quantity  of 
azote  which  seeds  contain  appears  to  be  on  the  increase, 
but  there  is  this  curious  difference  between  different  kinds, 
that  whilst  those  of  leguminous  plants,  sown  in  pure  earth 
and  moistened  with  nothing  but  distilled  water,  obtained  an 
increase  of  nitrogen  which  the  atmosphere  alone  could 
have  afforded,  those  of  barlev  and  other  cerealia  remained 
in  that  respect  stationary,  unless  manure  were  afforded.' 

"Boussingault  also  shows  in  a  subsequent  memoir,  that 
peas,  clover,  and  other  legumes  absorb  azote,  even  when 
planted  in  a  soil  that  contains  no  decomposing  animal  or 
vegetable  matter,  but  that  the  cerealia,  although  if  so 
placed,  they  may  grow,  do  not  appear  to  secrete  this 
principle. 

*' Boussingault,  however,  does  not  go  so  far  as  to  main- 
tain, that  the  latter  in  no  stage  of  their  existence  are  capa- 
ble of  discharging  this  function,  but  only  that  the  plant 
must  have  already  arrived  at  a  higher  state  of  vigor,  in 
order  to  derive  its  supply  from  such  a  source. 

"It  is  on  the  same  principle,  that  although  the  animal 
in  general  obtains  its  food  from  the  various  organic  bodies 
on  which  he  subsists,  yet  that  in  an  early  stage  of  existence, 
before  his  organs  are  fitted  for  undergoing  the  labor  of 
assimilating  such  materials,  nature  has  provided  him  in  his 
mother's  milk  with  aliment  already  almost  elaborated. 

"It  is  thus,  too,  that  in  the  seed  the  embryo  is  sur- 
rounded with  a  mass  of  albumen,  from  which  it  derives  its 
support,  until  its  roots  become  sufficiently  vigorous  to 
extract  nourishment  from  the  ground. 

"Hence  it  becomes  in  most  cases  necessary,  that  crops 


DAUBENY  ON  AMMONIA  OF  PLANTS.  267 

cultivated  as  articles  of  food  should  have  access  to  ven-e- 
table  or  animal  manure  from  which  they  may  derive  their 
azote,  but  as  this  supply  would  soon  be  exhausted,  were  it 
not  at  the  same  time  regenerated  from  the  atmosphere,  we 
see  the  advantage  of  intercalating  a  green  fallow  crop 
ploughed  into  the  ground  with  others  ;  as  leguminous 
plants,  according  to  the  experiments  of  Boussingault,  have 
the  greatest  power  of  absorbing  nitrogen  from  the  air. 

**On  the  same  principle  this  chemist  suggests  the  intro- 
duction of  the  Jerusalem  artichoke  into  light  soils,  which, 
owing  to  the  entire  absence  of  mould,  appear  irreclaimably 
barren;  this  vegetable,  the  tubers  of  which  afford  nourish- 
ment to  cattle  almost  equal  to  potatoes,  having  great  power 
of  absorbing  both  carbon  and  nitrogen  from  the  air,  and 
thus  by  degrees  generating  a  certain  amount  of  soil.^ 

*'Ihave  seen  this  vegetable  very  commonly  cultivated 
for  the  use  of  cattle,  in  the  light  lands  of  the  Grand  Duchy 
of  Baden,  and  in  certain  parts  of  Alsace. 

*'  But  if  it  be  true,  as  Liebig  has  endeavored  to  establish, 
that  plants  obtain  every  thing  except  their  alkalies  and 
earthy  constituents  from  the  atmosphere,  what,  it  may  be 
asked,  becomes  of  the  theory  that  attributes  the  unfitness 
of  a  soil  for  yielding  several  successive  crops  of  the  same 
plant  to  the  excre'tions  given  out  by  its  roots  ? 

**For  if  plants  receive  the  whole  of  their  volatilizable 
ingredients  from  the  atmosphere,  these  excrementitious 
matters,  being  composed  chiefly  of  carbon,  hydrogen,  and 
oxygen,  will  not  be  absorbed,  and  therefore  cannot  affect 
the  succeeding  vegetation. 

**The  above  inference  would  seem  unavoidable,  if  it 
were  considered  absolutely  proved,  that  nothing  but  the 
fixed  ingredients  of  a  plant  were  derived  from  the  earth, 
but  this  is  not  fully  established,  even  with  respect  to  the 
humus,  much  less  with  respect  to  the  more  soluble  matters 
which  the  soil  contains. 

*' These  latter,  there  seems  no  reason  for  doubting,  may 
be  taken  up  by  the  spongioles  of  the  roots  dissolved  in 

"  *  It  is  to  be  observed,  that  Boussingault  attributes  to  plants  the 
power  of  absorbing  nitrogen  from  the  air,  but  he  alleges  no  proof  that 
they  have  that  power,  and  his  results  may  be  just  as  well  explained 
by  supposing  them  to  have  different  powers  of  absorbing  ammonia. 
It  is  to  be  remarked,  that  the  helianthus  tuberosus  belongs  to  a  tribe 
of  plants  remarkable  for  their  power  of  absorbing  and  exhaling  water, 
and  hence  it  is  evident,  that  they  will  be  brought  into  contact  within  a 
given  time  with  a  larger  amount  of  ammonia,  than  other  plants,  which 
possess  a  less  degree  of  energy  in  that  respect." 


268  APPENDIX  TO  PART  I. 

water,  together  with  the  alkaline  and  earthy  ingredients 
which  are  derived  from  the  soil,  nor  am  I  aware  of  any 
proof  that  they  may  not  likewise  be  assimilated  when  so 
introduced. 

"The  theory  of  M.  Decandolle,  therefore,  is  not  affected 
by  the  above  experiments,  but  must  rest  on  its  own  merits, 
and  continue  to  afford  a  subject  for  inquiry  to  the  scientific 
agriculturist." 


Practical  Inferences.      From   Dr.  Dauheny^s   Lectures  on 
JigriculturCj  delivered  at  Oxford,  1841. 

'^The  first  inference  that  may  be  drawn,  relates  to  the 
utility  of  diligent  and  frequent  tillage,  in  order  to  favor  the 
disintegration  of  the  soil,  and  the  free  admission  to  it  of 
oxygen  and  of  water. 

"Unless  the  former  take  place,  no  fresh  alkali  can  be 
extracted  from  the  subjacent  rock  by  the  action  of  water 
upon  it  ;  unless  the  latter  be  brought  about  in  a  sufficient 
degree,  the  humus  excluded  from  air  cannot  undergo  that 
process  of  eremacausis,  or  gradual  combustion,  on  which 
its  influence  upon  the  nutrition  of  plants  has  already  been 
shown  to  depend. 

"Hence,  in  ancient  times,  the  importance  attached  to 
those  operations  which  had  this  object  for  their  aim,  — 

" '  Quid  est  agrum  bene  colere  ? '  asked  Cato.     *  Bene  arare.     Quid 
secundum?     Arare.     Quid  tertium ?     Stercorare.* 

Thus  ploughing  was  regarded  the  most  important  process 
in  agriculture,  after  which,  though  at  a  long  interval,  came 
manuring. 

"  The  design,  therefore,  of  the  agriculturist  is,  to  reduce 
the  soil  to  that  loose  and  crumbling  condition,  in  which  it 
becomes  entirely  pervious  to  air  and  moisture,  imparting  to 
it  the  quality  which  the  ancients  denominated  putre. 

**  *  Et  cui  putre  solum,  (naraque  hoc  imitamur  arando,) 
Optima  frumentis.' 

"Hence  the  superiority  of  spade  husbandry  over  the 
plough,  if  the  expense  of  the  labor  be  not  taken  into  the 
account  ;  hence  the  fertility  of  the  small  farms  of  the  ancient 
Romans,  notwithstanding  their  rude  methods  and  their 
deficiency  of  skill  ;  hence  the  fine  condition  of  those  tracts 
of  land,  which  are  subjected  to  the  unremitting  manual  ex- 
ertions of  societies  of  men  like  the  Trappists,  whose  mis- 


PRACTICAL  INFERENCES.  269 

taken  views  of  reliojion  have  led  them  into  that  entire  iso- 
lation  from  human  society,  under  which  even  the  severest 
physical  toil  becomes  itself  a  relief. 

*'  The  same  principle  explains  in  some  degree  the  utility 
of  subsoil-ploughing,  which,  by  bringing  up  to  the  surface 
a  portion  of  earth  previously  out  of  the  reach  of  those  in- 
fluences which  tend  to  cause  its  disintegration,  extracts 
from  it  the  alkaline  and  other  ingredients  required  by  the 
plant  for  its  subsistence. 

**  It  is  found  advantageous,  in  the  first  instance,  merely 
to  break  and  pulverize  the  subsoil  to  a  depth  of  eighteen 
or  twenty  inches,  without  bringing  it  to  the  surface,  and 
only  after  a  lapse  of  four  or  five  years  to  mix  it  with  the 
vegetable  mould  above,  a  practice,  the  utility  of  which  de- 
pends, not  only  on  the  mechanical  condition  of  the  land 
being  rendered  more  favorable  to  culture  in  consequence 
of  its  becoming  more  friable,  but  likewise,  probably,  owing 
to  the  chemical  decomposition  of  its  component  parts  having 
taken  place  more  completely. 

'*  Other  circumstances,  such  as  its  influence  on  the  drain- 
age of  the  land,  will  no  doubt  cooperate  in  producing  the 
benefit  which  often  results  from  the  practice  of  subsoiling  ; 
but  that  the  cause  pointed  out  really  contributes  to  its 
efficacy,  may  be  inferred  from  a  fact  attested  by  many  ex- 
perienced agriculturists,^  namely,  that  those  soils  are  most 
benefited  by  subsoil-ploughing,  which  can  be  rendered 
thereby  more  pervious  to  moisture,  and  consequently  to 
air  ;  whilst  those  which  contain  too  large  a  percentage  of 
clay  to  be  affected  in  this  manner  by  the  process,  derive 
no  advantage  from  it. 

**But  it  must  not  be  forgotten,  that  the  utmost  pains  be- 
stowed upon  its  elaboration  cannot  generate  any  new  prin- 
ciples, but  only  act,  by  enabling  the  soil  to  impart  more 
readily  to  the  crop  those  which  it  already  possesses. 

*'  This  obvious  truth  will  explain  the  cause  of  the  disap- 
pointment felt  by  farmers,  at  finding,  that  afler  a  certain 
time,  the  most  diligent  tillage  no  longer  affords  them  the 
same  returns  as  it  did  at  first. 

'*It  it  said,  that  Jethro  Tull,  who  first  proved  the  ad- 
vantages of  deepening  and  pulverizing  soils,  was  neverthe- 
less obliged  at  length  to  admit,  that  at  each  repetition  of 
the  experiment  the  success  was  less  decided,  unless  manure 
were  at  the  same  time  applied.     Judicious  tillage,  in  short, 

"  •  See  English  Agricultural  Journal^  No.  5,  p.  32." 

23* 


270  APPENDIX  TO  PART  I. 

like  the  use  of  machinery  in  the  arts,  does  not  create  any 
new  power,  but  only  tends  to  render  more  available  those 
already  latent  in  the  earth. 

"It  was  not  therefore  without  reason,  that  Cato,  after, 
as  we  have  seen,  pronouncing,  that  the  first,  and  the  second 
thing  in  agriculture,  is  to  plough,  adds,  that  the  third  is  to 
manure,  for  what  is  this  but  the  art  of  providing  for  the  in- 
tended crop  an  adequate  supply  of  those  ingredients  which 
enter  into  its  composition  ? 

"The  principles  therefore  which  have  been  laid  down, 
whilst  they  will  serve  to  guide  the  husbandman  in  the  se- 
lection of  his  fertilizers,  may  also  explain  the  different  re- 
sults that  are  obtained  from  the  use  of  the  same  kind  of 
mineral  manure  in  different  soils. 

"  Among  those  which  have  excited  the  greatest  interest 
within  the  last  few  years,  may  be  mentioned  the  nitrates  of 
potass,  and  of  soda. 

"The  former,  commonly  called  saltpetre,  is  produced 
spontaneously  in  most  parts  of  the  world,  and  especially  in 
hot  countries,  in  consequence  of  animal  and  vegetable 
decomposition  conducted  under  particular  conditions,  and 
accordingly  it  has  been  introduced  into  agriculture  from  an 
early  period.* 

"The  latter,  sometimes  distinguished  from  its  crystalline 
form,  as  cubic  nitre,  is  met  with  in  large  quantities  in  Peru, 
fourteen  leagues  from  the  port  of  Iquicque,  where,  ac- 
cording to  Mr.  Darwin,!  ^^  forms  a  stratum  two  or  three 
feet  thick,  lying  close  beneath  the  surface,  and  following 
the  margin  of  a  grand  basin  or  plain,  elevated  3300  feet 
above  the  level  of  the  Pacific,  but  which,  nevertheless, 
appears  evidently  to  have  been  at  one  time  a  lake,  or  in- 
land sea. 

"The  price  of  the  salt  at  the  ship's  side  in  1835,  at  the 
time  Mr.  Darwin  visited  the  spot,  was  fourteen  shillings  a 
cwt.,  the  grand  item  of  expense  being  its  transport  to  the 
coast.  J 

K  *  Where  the  price  operates  as  an  objection  to  its  use,  the  method 
of  forming  artificial  nitre-beds,  by  mixing  together  vegetable  and  ani- 
mal matters  in  a  state  of  decomposition  with  calcareous  earth,  may  be 
economically  adopted.  See  Cuthbert  Johnson,  on  Saltpetre  and  Ni- 
trate of  Soda,  Ridgway,  1840." 

"  t  See  Darwin's  Journal,  in  Voyage  of  the  Beagle." 
t  Mr.  J.  H.  Blake  of  Boston,  who  recently  visited  Peru,  informs  me, 
that  the  cost  of  the  nitrate  of  soda  was  ^  2.50  per  quintal,  and  that  it 
could  be  obtained  here  at  from  4^  to  5  cents  per  lb.  The  crude  nitrate, 
containing  from  70  to  80  per  cent,  of  the  pure  salt,  might  be  obtained 
here  at  2^  cents  per  lb.  —  fV. 


PRACTICAL  INFERENCES. 


271 


'*  These  particulars  are  perhaps  not  unimportant,  as  they 
may  serve  to  show  that  an  almost  unlimited  supply  of  both 
these  salts  may  be  calculated  upon,  and,  in  the  case  of  the 
nitrate  of  soda,  that  its  price  might  be  kept  down,  rather 
than  enhanced,  by  an  increased  demand. 

**That,  however,  with  which  the  agriculturist  is  most 
concerned,  is  to  determine  the  relative  value  of  these  salts 
as  manures,  and  to  discriminate  the  kind  of  land  to  which 
either  or  both  are  beneficial. 

**  Now,  it  is  remarkable,  that  the  nitrates,  whilst  they 
have  in  some  cases  occasioned  a  wonderful  increase  of  pro- 
duce, in  others  have  appeared  of  little  service,  and  also 
that,  whereas  on  certain  land  both  were  equally  efficacious, 
on  a  different  description  of  soil,  the  one  has  answered, 
whilst  the  other  failed. 

*'  For  a  great  deal  of  interesting  information  on  this  sub- 
ject, I  may  refer  to  the  Journal  of  the  Royal  Agricultural 
Society  of  England,  —  its  last  number*  more  especially: 
on  the  present  occasion  I  shall  confine  myself  to  noticing 
the  communication  of  Mr.  Hyett,  of  Painswick,  as  one, 
which  probably  points  to  the  true  cause  of  the  advantage 
derived  from  the  employment  of  these  salts. 

**Mr.  Hyett's  experiments  were  made  upon  the  stone  or 
cornbrash  of  Gloucestershire,  a  coarse  and  impure  oolitic 
limestone,  which  had  been  drilled  with  white  Sicilian  wheat 
in  the  autumn. 

**  Nitrate  of  soda,  at  the  rate  of  1  cwt.  to  the  acre,  was 
on  the  21st  of  April,  sown  and  hoed  in  over  all  the  field, 
excepting  two  square  portions,  which  were  staked  out,  and 
left  unnitrated. 

'*0n  the  16th  of  May  the  effect  of  the  salt  was  per- 
ceived, by  the  dark  green  color  of  the  plants. 

**  The  results  of  the  harvest  were  as  follows  : 


Produce. 

Measure  per  acre. 
Without  nitrate.    |       With  nitrate. 

Value  per  acre. 
Excess. 

Corn  clean  .  . 
tail   .  .  . 

total    .  . 

Bu.  Pks.  Pts. 

30.     2.     11 

2.     3.     11 

Bu.  Pks.   Pts. 

37.     3.      4 

5.    3.      7 

Bu.  Pks.  Pts. 
7.       0.        9 
2.     3.     12 

33.     2.      6     1      43.    2.     11      ]    10.      0.       5 

1           Weight.           1           Per  acre.           |                                   | 

Straw 

T.    Cwt.  qrs.   lbs. 
1.     3.     1.    21 

T.    Cwt.  qrs.   lbs. 
1.     11.     2.     3 

T.   Cwt.  qrs.    lbs. 
0.    8.     0.     10 

*'From  these  data  Mr.   Hyett  calculates,  that  the  in- 
creased value  of  the  produce,  arising  from  the  use  of  the 

<«*  For  January,  1841." 


272 


APPENDIX  TO  PART  I. 


nitrate  of  soda,  gives  a  profit  of  2/.  lis.  2d.  per  acre,  after 
deducting  I/.  3s.  Od.  for  the  value  of  the  salt  employed. 

**But  not  only  does  the  nitrate  increase  the  quantity  of 
the  grain,  but  it  tends  to  augment  those  ingredients,  which 
contain  the  largest  amount  of  nitrogen,  and  consequently 
afford  the  greatest  degree  of  nutriment,  namely,  the  gluten 
and  albumen. 

**This  is  shown,  by  the  analysis  of  the  nitrated,  and  non- 
nitrated  wheat,  made  by  a  chemist  at  his  request,  the  re- 
sults of  which  were  as  follows  : 


Wheat  on  which  the 

Wheat   on  which   no 

nitrate  was  used,  gave 

nitrate  was  used,  gave 

Bran 

25000 

24-000 

Gluten 

23  250 

19000 

Starch 

49-500 

55-500 

Albumen 

1-375 

•625 

Extract 

•375 

•250 

Loss  and  water  .  . 

•5 

•628 

100-  parts. 

100-  parts. 

**  Thus  it  is  seen,  that  in  the  nitrated  wheat  there  was 
4*25  per  cent,  more  gluten,  and  0*75  more  albumen,  than 
in  the  non-nitrated  sample. 

**  Considering,  then,  that  these  constituents  contain  nearly 
16  per  cent,  of  nitrogen,  we  are  justified  perhaps  in  at- 
tributing their  increase  to  the  decomposition  of  the  nitric 
acid  present  in  the  salt,  and  the  consequent  supply  of  nitro- 
gen in  greater  abundance  than  is  naturally  present  in  the 
soil. 

*' And  if  such  be  the  mode  of  its  operation,  it  may  be 
possible  to  explain  why  these  salts  should  appear  so  capri- 
cious in  their  effects  on  the  different  kinds  of  land  to  which 
they  have  been  applied. 

''  When  the  ground  already  contains  all  the  other  con- 
stituents which  the  plant  requires,  as,  for  instance,  a  suffi- 
cient amount  of  the  earthy  phosphates,  and  of  silicate  of 
potass,  the  addition  of  the  nitric  salt  will  do  good,  by  sup- 
plying nitrogen,  and  thus  enabling  the  vegetable  to  assimi- 
late a  proportionate  quantity  of  the  other  ingredients. 

"But  when  the  latter  are  already  nearly  exhausted,  the 
addition  of  the  nitrates  will  no  ^longer  be  of  advantage, 
since  only  that  portion  of  nitrogen  can  be  assimilated 
which  is  equivalent  to  the  amount  of  the  earthy  phosphates, 
of  the  silicate  of  potass,  and  of  the  other  fixed  ingredients, 
which  the  plant  obtains  from  the  soil. 


PRACTICAL  INFERENCES.  273 

**  Hence,  the  proper  remedy  in  such  a  case  would  seem 
to  be,  that  of  applying  some  other  manure,  which  may  fur- 
nish a  due  supply  of  the  deficient  matters. 

'*  Thus,  if  the  nitrates  have  failed,  we  should  be  inclined 
to  try  the  next  year  the  effect  of  phosphate  of  lime,  or  of 
animal  manure,  upon  the  same  soil. 

*'  But  it  seems  to  happen  sometimes,  that  the  same  land, 
which  is  benefited  by  the  administration  of  one  kind  of  nitric 
salt,  is  scarcely  affected  by  another. 

*'This  anomaly  presented  itself  in  an  experiment  on  a 
small  scale,  which  was  tried  at  my  request,  by  my  broth- 
er, the  Rev.  E.  Daubeny,  on  his  farm,  in  the  vicinity  of 
Cirencester. 

"The  subsoil  is  a  stiff  retentive  clay,  resting  upon  the 
cornbrash  limestone,  and  the  farm,  before  it  came  into  its 
present  occupation,  was  in  an  exhausted  condition,  though 
it  has  latterly  yielded  somewhat  better  returns. 

**  A  coarse  analysis  of  a  sample,  conducted  according  to 
the  method  recommended  by  Mr.  Rham,  in  the  Journal  of 
the  English  Agricultural  Society,*  afforded  me  the  follow- 
ing results  : 

"  1000  grains  contained,  607,  of  impalpable  powder,  consisting  of 
Water  .  .  .  .  .57 

Humus    .  .  .  .  .57 

Silica  .  .  .  .  .64 

Alumina  mixed  in  the  silica       .  .  24 

Oxide  of  iron  .  .  .  .19 

Carbonate  of  lime  ...  90 

Magnesia      ....  a  trace 

Clay        .....  296 

Total       .  .  .  .  .607 

And  388  of  coarser  materials,  separated  by 
Sieve         .  .       No.  1.  the  coarsest  117"^  consisting 

Sieve  .  No.  2.     .  .151     chiefly  of 

Sieve        .  .       No.  3.  the  finest      120  j^clay,  with 

[50  grs.  of 

Total        .  .  .  .         .       388  j  carbonate 

Loss  ....  5  J  of  lime. 

**Four  equal  strips  of  this  land,  each  somewhat  ex- 
ceeding J  of  an  acre,  and  contiguous  one  to  the  other, 
which  had  been  sown  with  wheat  in  the  autumn  of  1839, 
were  measured  out. 

"The  first  of  these,  which  lay  next  to  the  hedge,  was 
left  without  any  addition  of  manure. 

*'The  second,  adjoining,  had  a  top-dressing  of  J  cwt.  of 
nitrate  of  potass  given  it  in  April. 


(( » 


Number  1,  page  46." 


274  APPENDIX  TO  PART  I. 

*'The  third  portion  was  left,  like  the  first,  without 
addition. 

**The  fourth,  or  that  farthest  from  the  hedge,  had  a 
similar  top-dressing  of  nitrate  of  soda  applied  at  the  same 
period. 

**  The  salts  were  respectively  scattered  over  the  strips 
of  land  in  as  uniform  a  manner  as  possible,  and  became 
diffused  through  the  soil,  by  means  of  the  showers  which 
followed  shortly  after  their  application. 

*' As  the  wheat  advanced  towards  maturity,  the  nitrated 
patches  were  distinguishable,  by  the  more  vivid  greenness 
of  the  crop,  and  by  its  standing  up  somewhat  above  the 
general  level,  but  this  difference  was  less  perceptible  at  a 
later  stage  of  its  progress. 

'*  In  the  autumn  the  whole  was  reaped  as  usual,  and  the 
following  results  obtained  : 

**  No.  1.  produced  only  5  bushels,  54  lbs.  of  grain,  or  23 
bushels,  36  lbs.  to  the  acre,  but  the  crop  had  been  ac- 
cidentally trodden  by  sheep,  and  much  devoured  by  birds. 
The  straw  was  not  weighed. 

*'No.  2.  produced  7  bushels,  51  lbs.,  or  31  bushels,  48 
lbs.  to  the  acre,  and  520  lbs.  of  straw  =  1  ton,  0  cwt.  80  lbs. 
to  the  acre. 

*'No.  3.  produced  6  bushels,  54  lbs.,  or  27  bushels,  36 
lbs.  to  the  acre,  and  421  lbs.  of  straw  =  16  cwt.  to  the  acre. 

**No.  4.  produced  6  bushels,  48  lbs.,  or  27  bushels, 
12  lbs.  to  the  acre,  and  432  lbs.  of  straw  =  15  cwt.  48  lbs. 
to  the  acre. 

'*  With  respect  to  weight,  that  of  No.  2.  was  62|  lbs.  to 
the  bushel,  that  of  No.  3.  and  4.  was  only  62  lbs. 

**Now  3 J  lbs.  of  flour  from  No.  3,  produced  of  bread 
4  lbs.  4  ozs. 

'*  Whereas  3J  lbs.  from  No.  2.  produced  4  lbs.  14  ozs. 

'*  Hence  the  difference,  between  the  produce  of  the  strip 
of  ground  which  had  been  manured  with  nitrate  of  potass, 
and  that  which  had  received  no  manure,  may  be  calculated 
as  follows : 

'*  Amount  of  produce,  of 
Bu.    lbs. 

''No.  3       6      54  =  6. 

''No.  2       7      57  =  7. 

"  As  6  :  7  :  :  100  :  120,  or  20  per  cent,  of  increase  in  the 
amount  of  produce. 

"To  which  add,  that  the  quantity  of  flour,  that  in  No. 


PRACTICAL  INFERENCES.  275 

3  had  produced  4  lbs.  4  ozs.  of  bread,  in  No.  2.  produced 

4  lbs.  14  ozs.     Now 

*'  As  4  lbs.  4  ozs.  :  4  lbs.  14  ozs.  :  :  100  :  1 14. 

'*  Showing  an  increase  per  cent,  of  14 -j- 20  =  34  per 
cent. 

*'Now  if  we  calculate  the  wheat  as  worth  eight  shillings 
a  bushel,  the  profit  of  using  the  nitrate  of  potass  will  stand 
as  follows  : 

*'27  bushels  36  lbs.  at  8.s.  =  11Z.  value  of  the  produce  on 
the  non-nitrated  land  :  add  34  per  cent,  or  Jrd  =  3/.  135. 
4d.,  for  the  value  of  the  nitrated,  which,  after  deducting 
1/.  10*.  for  the  value  of  a  cwt.  of  nitrate  of  potass,  and  for 
carriage,  will  leave  to  the  farmer  a  clear  profit  of  2/.  3s.  4d. 

*'  The  superior  absorbing  power  of  the  nitrated  flour, 
over  the  non-nitrated^  was  found  to  depend  upon  the  pres- 
ence of  a  larger  amount  of  gluten,  for  I  discovered  in  the 
former  740  grs.  in  the  pound,  or  13  per  cent.  ;  in  the  latter 
850  grs.  in  the  pound,  or  15  per  cent,  of  that  ingredient, 
the  difference  being  2  per  cent,  in  favor  of  the  nitrated 
wheat,  a  result  which  confirms,  in  a  very  satisfactory  man- 
ner, the  statement  of  Mr.  Hyett.* 

**But  how  are  we  to  account  for  the  failure  of  the  nitrate 
of  soda,  on  soil  which  had  been  so  materially  benefited  by 
the  administration  of  nitrate  of  potass  ^ 

**The  small  scale  upon  which  the  experiment  was 
conducted,  may  render  us  reluctant  to  build  much  upon 
the  results  obtained,  until  it  has  been  again  repeated,  but 
supposing  the  fact  to  be  hereafter  confirmed,  I  can  only 
conjecture,  that  the  diflference  must  have  arisen  from  a 
deficiency  in  the  land,  of  potass,  which  would  be  supplied 
by  the  saltpetre,  but  not  by  the  nitrate  of  soda.  |  Should 
this  be  the  true  solution,  those  soils,  in  which  nitrate  of  soda 
has  succeeded,  ought  to  contain  a  larger  quantity  of  potass, 
than  those  in  which  it  has  failed. 

**The  general  principles  laid  down  may  also  inform  us, 
as  to  the  true  plan  upon  which  the  succession  of  our  crops 
should  be  regulated. 

**  Those  plants  ought  to  succeed  each  other,  which  con- 
tain different  chemical  ingredients,  so  that  the  quantities 

"  *  The  amount  of  gluten  is  smaller  than  in  the  samples  reported  on 
by  Mr.  Hyett,  but  my  gluten  was  dried,  with  the  greatest  care,  under 
the  exhausted  receiver  of  an  air-pump,  with  sulphuric  acid,  till  it 
ceased  to  lose  weight." 

"  t  Nitrate  of  soda  is  stated  to  exist  in  barley,  but  it  has  not  been  de- 
tected in  wheat.  It  would  therefore  be  worth  while  to  see,  whether 
the  above  salt  is  particularly  suited  to  the  former  crop." 


276  APPENDIX  TO  PART  I. 

of  each,  which  the  soil  at  any  given  time  contains,  may  be 
absorbed  in  an  equal  ratio. 

**Thus  a  productive  crop  of  corn  could  not  be  obtained, 
without  the  phosphates  of  lime  and  magnesia  which  are 
present  in  the  grain,  nor  without  the  silicate  of  potass  which 
gives  stability  to  the  stalks. 

**It  would  be  injudicious,  therefore,  to  sow  any  plant 
that  required  much  of  any  of  the  above  ingredients,  imme- 
diately after  having  diminished  the  amount  of  them  present 
in  the  soil,  by  a  crop  of  wheat,  or  of  any  other  kind  of  corn. 

**But,  on  the  other  hand,  leguminous  plants,   such  as' 
beans,  are  well  calculated  to  succeed  to  crops  of  corn,  be- 
cause they  contain  no  free  alkalies,  and  less  than  one  per 
cent,  of  the  phosphates. 

**  They  thrive,  therefore,  even  where  these  ingredients 
have  been  withdrawn,  and  during  their  growth^  afford  time 
for  the  ground  to  obtain  a  fresh  supply  of  them,  by  a  fur- 
ther disintegration  of  the  subjacent  rock. 

*'  For  the  same  reason,  wheat  and  tobacco  may  some- 
times be  reared  in  succession  in  a  soil  rich  in  potass,  be- 
cause the  latter  plant  requires  none  of  those  phosphoric 
salts  which  are  present  in  wheat. 

"In  order,  however,  to  proceed  upon  certain  data,  it  would 
be  requisite,  that  an  analysis  of  the  plants  most  useful  to 
man  should  be  accomplished  in  the  different  stages  of  their 
growth,  a  labor  which  has  hitherto  been  only  partially  un- 
dertaken, and  which  perhaps  is  an  object  worthy  to  engage 
the  attention  of  a  great  Body,  like  that  of  the  English  Ag- 
ricultural Association. 

**  It  is  a  curious  fact,  that  the  same  plant  differs  in  con- 
stitution when  grown  in  different  chmates.  Thus  in  the 
beet-root,  nitre  takes  the  place  of  sugar,  when  this  plant  is 
cultivated  in  the  warmer  parts  of  France.* 

"The  explanation  of  this  difference  is  probably  as  fol- 
lows :  — 

"Beet-root  contains,  as  an  essential  ingredient,  not  only 
saccharine  matter,  but  also  nitrogen,  and  it  is  probable, 
that  the  two  are  mutually  so  connected  together  in  the  veg- 
etable tissue,  that  the  one  cannot  exist  without  the  other. 
The  nitrogen,  being  derived  from  the  decomposition  of  am- 
monia, must  be  affected  by  any  cause  which  diminishes  the 
supply  of  the  latter  ;  and  in  proportion  as  this  ingredient 
is  wanting,  the  secretion  of  sugar  will  likewise  fall  off. 

"Now,  it  has  been  shown  by  Liebig,  that  the  formation 

"*  See  Chaptal." 


PRACTICAL  INFERENCES.  277 

of  nitric  acid  is  owing  to  the  decomposition  of  ammonia, 
and  it  is  conceived  by  him,  that  the  last  products  of  the  de- 
composition of  animal  bodies  present  themselves,  in  the 
form  of  ammonia  in  cold,  and  in  that  of  nitric  acid  in  warm 
climates.  *  Hence,  in  proportion  to  the  amount  of  nitric 
acid  formed,  and  of  nitre  absorbed  by  the  plant,  that  of  the 
nitrogen,  and  consequently  that  of  the  saccharine  matter, 
present  in  it,  may  be  diminished. 

*'We  may  also  be  guided  in  the  management  and  selec- 
tion of  manures,  by  the  principles  above  laid  down.  The 
solid  excrement  of  animals  varies  of  course  in  composition 
according  to  the  nature  of  their  food  :  thus  that  of  herbivo- 
rous animals,  which  are  fed  principally  on  grasses,  contains 
much  silicate  of  potass,  as  well  as  phosphoric  salts,  but 
comparatively  little  nitrogen  ;  whilst  human. faeces  contain 
little  of  the  former  ingredient,  but  much  phosphate,  and  a 
larger  proportion  of  nitrogen.  There  will  be  seen  even  a 
difference  in  these  respects  between  the  manure  afforded  by 
the  inhabitants  of  towns,  fed  principally  upon  animal  food, 
and  that  of  peasants,  who  subsist  in  a  greater  degree  upon 
vegetables. 

*'In  like  manner,  the  excrement  of  cattle  is  more  effica- 
cious as  manure,  when  the  animal  is  well  fed,  and  under- 
going the  fatting  process,  than  when  it  is  more  scantily 
nourished. 

'*  According  to  Sprengel,  there  is  a  difference  between 
different  kinds  of  herbivorous  animals  in  this  respect,  cows 

*  "  I  have  seen  no  attempt  to  account  for  the  formation  of  nitrate  of 
soda  in  such  large  quantities  in  Peru,  and  may  therefore  offer  the  fol- 
lowing, as  at  least  a  plausible  solution. 

*'  Wherever  salt  lakes  occur,  which  become  partially  or  wholly  dried 
up  during  a  part  of  the  year,  carbonate  of  soda  will  be  formed  from  the 
decomposition  of  common  salt.  This  I  have  observed  myself  on  the 
sandy  plains  of  Hungary,  in  the  neighborhood  of  Pesth.  Now  if  any 
circumstances  should  concur  in  such  spots,  calculated  to  generate  nitric 
acid,  the  latter,  by  its  stronger  affinity  for  the  alkali,  would  take  the 
place  of  the  carbonic  acid,  and  nitrate  of  soda  would  result. 

"  This,  however,  being  a  deliquescent  salt,  would  not  accumulate  on 
the  surface,  except  in  countries  like  Peru,  remarkable  for  their  extreme 
dryness. 

"  But  how  are  we  to  account  for  the  generation  of  so  large  a  quanti- 
ty of  nitric  acid  in  this  locality .'' 

"  If  we  suppose  with  Mr.  Darwin,  that  the  district  in  which  the  salt 
is  found  was  once  a  lake  or  inland  sea,  its  change  to  dry  land  must  have 
caused  the  destruction  of  all  its  marine  inhabitants.  Now  the  decom- 
position of  their  exuviae  would,  in  a  warm  climate,  present  themselves, 
as  stated  in  the  text,  in  the  form,  rather  of  nitric  acid,  than  of  ammonia. 

"  Hence  the  production  of  so  much  nitrate  of  soda  in  Peru,  is  attrib- 
utable to  the  heat ;  its  preservation  to  the  dryness  of  the  climate." 

24 


278  APPENDIX  TO  PART  L 

requiring,  for  the  chemical  constitution  of  their  body,  or 
for  the  formation  of  their  milk,  more  nitrogen,  and  more 
phosphate  of  lime,  than  sheep  ;  whilst  the  latter  require 
again  more  sulphur,  and  more  common  salt,  for  the  forma- 
tion of  their  wool.  Hence  the  excrements  of  oxen  contain 
less  nitrogen  than  those  of  sheep,  whilst  they  are  more 
abundant  in  salt  and  sulphur. 

'*  Accordingly  it  is  found  in  practice,  that  sheep's  dung 
ferments  more  readily  than  that  of  black  cattle.  '  The 
latter,  therefore,'  says  Liebig,  'is  of  most  service  on  soils 
consisting  of  lime  and  sand,  which  contain  no  silicate  of 
potass  or  phosphates,  whilst  their  value  is  much  less  when 
applied  to  soils  formed  of  argillaceous  earth,  basalt,  gran- 
ite, porphyry,  clinkstone,  and  even  mountain  limestone, 
because  all  these  contain  potass  in  considerable  quantity.' 

**  Human  excrements,  on  the  contrary,  are  useful  in 
both  descriptions  of  soil,  but  would  be  inadequate  to  supply 
the  silicate  of  potass  which  is  wanting  in  the  former. 

**The  constituents,  however,  to  which  the  solid  excre- 
ments of  animals  in  general  owe  their  principal  efficacy 
are  the  earthy  phosphates  ;  and  hence  we  see,  why  it  is 
that  animal  manure  should  favor  the  growth  of  corn,  which 
contains  so  much  phosphate  of  lime  and  magnesia,  and 
why  the  earth  of  bones,  and  even  the  ashes  of  certain 
kinds  of  wood,  such  as  the  beech,  which  contain  phos- 
phates, may  be  advantageously  substituted,  whilst  the  ash- 
es of  others,  as  of  the  oak  and  fir,  which  are  deficient  in 
the  phosphates,  are  of  very  little  avail. 

"  We  see  also  the  cause  of  the  fertilizing  quality  of 
liquid  manure,  as  employed  in  Holland,  for  those  crops 
which  are  most  subservient  to  the  nourishment  of  man. 

*' Liquid  manure  consists  in  a  great  degree  of  the  urine 
of  various  animals,  which,  during  its  decomposition,  exhales 
a  larger  quantity  of  ammonia  than  any  other  species  of 
excrement. 

"  Now  all  kinds  of  corn  contain  nitrogen,  and  conse- 
quently any  manure  which  yields  a  ready  supply  of  ammo- 
nia, must  cause  a  fuller  development  of  those  parts  of  the 
plant  which  are  of  the  greatest  use  to  man. 

*'Even  the  kind  of  animal  manure  usually  employed  in 
this  country  owes  its  efficacy,  so  far  as  it  is  dependent 
upon  the  ammonia  present,  to  the  urine,  rather  than  to  the 
solid  excrement,  of  which  it  is  made  up,  and  hence  be- 
comes materially  deteriorated  in  this  respect,  when  the 
more  liquid  portions  are  allowed  to  drain  off  from  it. 


PRACTICAL  INFERENCES.  279 

**We  may  also  derive  from  these  considerations,  some 
useful  cautions,  as  to  the  treatment  of  this  same  material. 

*' Ammonia,  in  the  free  or  uncombined  condition  in  which 
it  is  generated  from  the  decomposition  of  animal  substances, 
is  caustic  and  noxious  to  vegetation,  and  is  likewise  so 
volatile  that  it  will  escape  into  the  atmosphere  so  soon  as 
it  is  produced,  unless  some  means  are  taken  to  detain  it. 

*'This  causticity  is  readily  removed  by  promoting  its 
combination  with  the  carbonic  acid  of  the  atmosphere,  but 
to  prevent  its  escape  during  the  time  necessary  for  effect- 
ing this  union,  various  expedients  have  been  resorted  to. 

*' Where  water  in  sufficient  quantity  is  present,  along 
with  the  other  materials  of  the  dung-heap,  this  alone  will 
in  some  measure  tend  to  prevent  its  volatilization,  and  the 
same  object  is  further  secured,  by  admixture  with  peat,  as 
recommended  by  Lord  Meadowbank,  or  with  sawdust, 
tanner's  bark,  turf,  and  other  similar  substances.  These 
too  are  beneficial,  not  only  by  moderating  the  putrefactive 
process,  but  also  by  detaining  the  ammonia  generated 
within  their  pores,  and  thus  preventing  its  loss. 

"The  advantage  of  compost  heaps,  which  are  strongly 
advocated  by  some  farmers,  depends  mainly  on  these  prin- 
ciples. 

*'The  method  recommended  by  a  writer,  in  a  late  num- 
ber of  the  English  Agricultural  Journal,*  to  whom  a  prize 
of  ten  sovereigns  was  awarded  for  his  Essay,  consisted,  in 
first  making  a  substratum  of  peat  |ths,  and  sawdust  Jth  ; 
spreading  over  it  the  dung  from  the  cattle-sheds,  and  the 
urine  preserved  for  the  purpose  in  tanks  contiguous  ;  and 
then,  after  allowing  the  mixture  to  remain  exposed  for  a 
week,  covering  it  with  a  fresh  layer,  nine  inches  or  a  foot 
thick,  of  peat  and  sawdust,  or  of  peat  alone. 

**  Several  such  alternations  of  peat  and  manure  are  to 
be  piled  one  above  the  other  during  the  winter,  great  care 
being  always  taken,  that  the  peat  should  be  as  dry  as  pos- 
sible, by  exposing  it  previously  for  several  months  to  the 
weather. 

*'Now  it  will  be  immediately  perceived,  that  these 
recommendations  of  a  practical  farmer  completely  fulfil 
the  conditions,  which  theory  suggests,  for  making  the  best 
use  of  our  manure,  by  first  neutralizing  the  ammonia,  and 
afterwards  detaining  it  within  the  pores  of  a  spongy  sub- 
stance, until  it  is  spread  over  the  land. 

"The  most  eflfectual  plan,  however,  of  preventing  its 

"*  Part  II   p.  135." 


280  APPENDIX  TO  PART  I. 

loss,  would  seem  to  be,  not  to  wait  for  the  slower  action 
of  carbonic  acid  upon  it,  but  to  combine  it  directly  with 
those  acids,  which  form  with  it  salts  fixed  at  common  tem- 
peratures. 

**  Hence,  Liebig  advises  the  addition  of  sulphuric  or  of 
muriatic  acid,  both  cheap  substances,  to  the  other  materials 
of  the  dung-heap,  which,  forming  with  the  ammonia  pres- 
ent, the  sulphates  and  muriates  of  that  alkali,  would  at 
once  prevent  any  loss  of  it  by  evaporation. 

*'  If  these  expedients  be  not  adopted,  it  should  at  least  be 
borne  in  mind,  that  unless  means  are  taken  to  prevent  it,, 
the  most  valuable  portion  of  the  manure  is  constantly 
escaping,  during  exposure  to  air  and  sun,  by  evaporation, 
and  also  by  draining  off  into  the  ground,  whence,  instead 
of  a  material  calculated  to  afford  a  ready  supply  of  nitro- 
gen to  the  plant,  we  obtain  an  effete  mass,  in  which  that 
element  is  in  a  great  measure  wanting,  and  which,  there- 
fore, can  only  influence  the  growth  of  plants,  by  virtue  of 
the  phosphoric  salts  and  other  fixed  ingredients  still  pres- 
ent in  it. 

*'  These  views  also  throw  some  new  light  upon  the  use 
of  gypsum,  or  sulphate  of  lime,  as  a  manure  to  certain 
crops. 

*'  The  fact,  that  leguminous  plants  contain  this  substance 
as  an  essential  ingredient,  may  in  some  measure  explain 
its  fertilizing  effect  on  them,  but  it  is  also  found  serviceable 
to  turnips  and  cabbages,  which  do  not  appear  to  contain  it, 
nor  does  it  seem  easy  thus  to  explain  the  superior  advan- 
tage said  to  arise,  from  scattering  it  in  fine  powder  over 
the  leaves  of  clover  and  saintfoin,  as  is  practised  in  France 
and  in  North  America,  and  with  such  manifest  good  effect, 
that,  it  is  said,  if  the  substance  be  partially  applied  to  a 
field,  the  portions  that  have  received  this  dressing  may 
afterwards  be  distinguished  from  the  rest  by  the  superior 
luxuriance  of  the  crop. 

''Liebig,  therefore,  has  suggested  another  mode  in 
which  gypsum  may  be  beneficial  to  crops  in  general,  by 
reference  to  the  property  which  it  possesses,  of  depriving 
ammonia  of  its  volatility,  and  thus  preventing  its  escape 
into  the  atmosphere. 

*'This  effect  arises  from  the  double  decomposition  which 
takes  place,  when  sulphate  of  lime  and  carbonate  of  ammo- 
nia are  brought  together,  the  lime  being  converted  into  a 
carbonate,  and  the  ammonia  uniting  with  sulphuric  acid. 

' '  The  above  theory  of  its  use  being  admitted,  we  may 


PRACTICAL  INFERENCES.  281 

be  encouraged  to  extend  its  application  to  other  crops 
besides  the  Leguminosae,  and  also  to  mix  it  with  the  dung 
of  our  stables,  so  as  to  prevent  the  waste  of  this  valuable 
material,  which  is  constantly  occurring.     (See  p.  191.) 

"  But  the  farmer  must  be  reminded,  that  it  will  be  neces- 
sary, that  the  sulphate  of  ammonia  resulting  from  the 
action  of  the  gypsum,  should  be  brought  into  contact  with 
some  substance  capable  of  slowly  decomposing  it,  so  as  to 
supply  ammonia  to  the  plant. 

"For  there  is  no  reason  to  believe,  that  the  organs  of  a 
vegetable  can  decompose  sulphate  of  ammonia,  and  if  they 
were  able  so  to  do,  the  disengagement  of  free  sulphuric 
acid  in  consequence  could  hardly  fail  to  be  injurious  to 
their  structure. 

**Now  a  soil  consisting  of  pure  sand,  or  of  clay,  would 
be  incapable  of  acting  upon  this  salt,  but  contradictory  as 
it  may  seem  to  the  fact,  that  carbonate  of  ammonia  is 
decomposed  by  sulphate  of  lime,  carbonate  of  lime  does 
appear  in  a  slight  degree  to  disengage  ammonia  even  in 
the  cold,  as  may  be  seen  by  the  change  of  color  produced 
in  a  piece  of  turmeric  or  reddened  litmus  paper,  placed 
over  a  vessel  containing  powdered  chalk,  as  soon  as  it  is 
moistened  with  a  solution  of  sulphate  of  ammonia. 

**And  since  this  interchange  of  constituents  is  effected 
rapidly  under  the  influence  of  a  high  temperature,  as  hap- 
pens in  the  common  method  of  obtaining  carbonate  of 
ammonia  artificially  by  double  decomposition,  it  is  worth 
inquiry,  whether  it  may  not  be  favored  likewise  by  exposure 
to  solar  heat  and  light. 

**  Where  calcareous  matter,  therefore,  exists  in  the  soil, 
ammonia  may  be  slowly  supplied  in  this  manner  to  the 
growing  plant,  and  it  is  possible  even,  that  the  carbonate 
of  lime,  which  seems  to  be  generally  present  in  the  sap, 
may  act  in  the  same  manner. 

'*In  this  ^yay  we  may  readily  explain  the  use  of  scatter- 
ing gypsum  over  the  leaves  of  clover  shortly  before  a 
shower  of  rain.  The  ammonia  present  in  the  latter  is  thus 
detained,  and  converted  into  sulphate  by  the  action  of  the 
gypsum  upon  it,  and  when  introduced  into  the  system  by 
the  absorbing  surfaces  of  the  plant,  it  may  be  again  con- 
verted into  carbonate,  by  the  slow  action  of  the  carbonate 
of  lime  present  in  the  sap. 

*' When,  however,  a  more  rapid  disengagement  of  am- 
moniacal  gas  is  required  for  the  nutrition  of  the  intended 
crop,  we  ought  not  to  trust  to  the  slow  action  of  carbonate 

24* 


282  APPENDIX  TO  PART  I. 


of  lime,  but  should  apply  quicklime  to  the  spots  over  which 
the  manure  has  been  scattered. 

**It  is  probably  in  part  by  setting  at  liberty  the  volatile 
alkali  imprisoned  in  the  soil,  that  quicklime  acts  so  bene- 
ficially in  agriculture,  and  in  particular,  that  it  improves 
soil  containing  a  free  acid,  such  as  peat  earth  ;  for,  inde- 
pendently of  its  use  in  neutralizing  a  substance,  which 
checks  vegetation  by  its  antiseptic  properties,  quicklime 
may  also  disengage  a  portion  of  ammonia  combined  with 
this  acid,  and  thus  afford  to  the  plant  a  more  abundant 
supply  of  the  nitrogen,  which  it  requires. 

"Chloride  of  calcium,  common  salt,  sulphuric  and  mu- 
riatic acids,  phosphate  of  lime,  and  other  salts,  may,  it 
would  seem,  on  the  principles  laid  down,  be  substituted, 
when  gypsum  cannot  be  obtained. 

**The  chlorides,  indeed,  like  certain  oxides,  (such  as 
water  and  carbonic  acid,)  seem  to  be  decomposed  by  the 
plant  under  the  influence  of  light,  for  chlorine  is  exhaled 
by  vegetables  near  the  sea,  as  oxygen  is  in  other  situations. 
Hence,  if  muriate  of  ammonia  should  result  from  the 
action  of  common  salt  upon  the  carbonat^e  of  ammonia 
present  in  rain,  it  may  undergo  decomposition  when  ab- 
sorbed by  the  plant,  and  contribute  in  consequence  to  sup- 
ply it  with  nitrogen. 

*'The  above  considerations  may  suggest  to  us  the  utility 
in  agriculture  of  ammoniacal  compounds  of  all  kinds,  as 
substitutes  for  animal  manure. 

''Sal  ammoniac  is  probably  too  expensive  an  article  to 
be  employed  ;  but  sulphate  of  ammonia  may  be  had  of  the 
wholesale  chemist  at  a  price  considerably  more  reasonable, 
namely,  at  22/.  per  ton  ;  and  the  ammoniacal  liquor,  which 
is  afforded  in  abundance  by  our  gas  manufactories,  through 
the  distillation  of  coal,  is  a  still  cheaper  commodity. 

*'The  latter  consists  principally  of  carbonate  of  ammo- 
nia, mixed  with  a  certain  proportion  of  the  hydro-sulphuret, 
and,  until  its  use  in  agriculture  was  discovered,  much  of  it 
was  allowed  to  run  waste  into  the  Thames,  where  its  nox- 
ious qualities  destroyed  the  fish,  and  rendered  the  water 
unpalatable  and  disgusting. 

"  Its  efficacy  as  a  manure  is  vouched  for  by  many  who 
have  made  trial  of  it  upon  their  land,*  and  although  the 
hydro-sulphuret  of  ammonia  in  a  concentrated  form  would 
doubtless  be  fatal  to  vegetation,  yet  in  a  proper  state  of 

"  *  See  a  communication  by  Mr.  Paynter,  on  Gas-water  as  a  Manure, 
Eng.  Agricult.  Journ.  No.  1,  p.  4." 


PRACTICAL  INFERENCES.  283 

dilution  it  may  be  of  service  to  certain  crops,  not  merely 
by  virtue  of  the  ammonia,  but  also  in  consequence  of  the 
sulphuretted  hydrogen,  which  it  contains,  since  the  latter 
is  found  to  be  an  ingredient  in  the  turnip,  and  in  some 
other  tribes  of  cruciferous  plants. 

"Where,  however,  it  is  found  troublesome  to  preserve, 
or  difficult  to  convey  to  a  distance  this  volatile  material,  an 
easy  method  presents  itself  for  retaining  for  any  length  of 
time  the  ammonia  present  in  it. 

"This  is  done,  by  availing  ourselves  of  the  same  prin- 
ciple which  has  been  already  explained  to  you,  in  treating 
of  the  uses  of  gypsum  as  a  manure  ;  for  as  the  gas  liquor 
consists  of  ammonia,  combined  principally  with  carbonic 
acid,  it  is  evident,  that  it  may  be  converted  into  a  sulphate 
by  admixture  with  sulphate  of  lime. 

"lam  indebted  to  an  excellent  scientific  chemist*  for 
the  following  details,  which  may  be  of  use  to  the  agricul- 
turist in  enabling  him  to  appreciate  the  importance  of  this 
commodity,  and  to  prepare  for  himself  any  quantity  that  he 
may  require  for  his  farm. 

"One  gallon  of  the  ammoniacal  liquor  added  to  1  lb.  2-| 
ozs.  of  powdered  but  not  calcined  gypsum,  will  produce 
1  lb.  of  crystallized  sulphate  of  ammonia.  To  effect  the 
decomposition,  the  materials  should  be  mixed  and  stirred 
up  together  for  ten  or  twelve  hours,  a  heat,  below  that  of 
ebullition,  being  at  the  same  time  employed.  The  sulphate 
of  ammonia  remains  in  solution,  and  may  be  obtained  in  a 
solid  state,  by  evaporating  at  a  low  temperature. 

"Theory  would  suggest,  that  this  material  ought  to  sup- 
ply nitrogen  to  the  crop  at  a  much  cheaper  rate  than  the 
nitrates  employed  for  that  purpose.  For  let  us  suppose, 
that  the  farmer  wishes  to  add  to  his  land  60  lbs.  of  crys- 
tallized sulphate  of  ammonia.  This  may  be  obtained  by 
introducing  about  70  lbs.  of  powdered  gypsum  uncalcined 
into  50  gallons  of  ammoniacal  liquor  ;  for  my  informant 
found,  that  one  gallon  mixed  with  chloride  of  calcium 
yielded  4800  grs.  of  carbonate  of  lime,  equivalent  to  about 
7200  grs.  of  crystallized  sulphate  of  ammonia,  or  1  lb.  3 
ozs.  Now  4800  grs.  of  carbonate  of  lime  are  equivalent 
to  8250  grs.,  or  to  1  lb.  5  ozs.  of  sulphate  of  lime,  with  2 
atoms  of  water. 

"This,  therefore,  is  the  quantity  of  gypsum  required,  to 

"  *  Mr.  Richard  Phillips,  the  superintendent  of  the  chemical  depart- 
ment of  the  establishment,  connected  with  the  Museum  of  Economic 
Geology,  lately  instituted  by  government." 


284  APPENDIX  TO  PART  I. 

convert  the  contents  of  1  gallon  of  gas  liquor  into  sulphate 
of  ammonia,  and  accordingly,  50  gallons  will  require  70 
lbs.  of  gypsum,  and  will  produce  about  60  lbs.  of  the  am- 
moniacal  sulphate. 

**Now  since  the  price  per  ton  of  gypsum  is  from  2Z.  to 
3/.,  the  cost  of  70  lbs.  of  it  cannot  exceed  2».,  and  the 
labor  of  mixing  the  materials  may  be  reckoned  at  about  as 
much  more  ;  so  that  to  a  gas  company,  where  this  liquor, 
not  being  employed  for  manufacturing  any  of  the  salts  of 
ammonia,  has  hitherto  been  regarded  as  so  much  refuse, 
and  where  the  heat  requisite  for  evaporating  and  crystal- 
lizing the  product  can  be  obtained  with  scarcely  any  in- 
creased expenditure,  the  cost  of  the  impure  sulphate  would 
not  exceed  one  penny  per  pound. 

'*  This  then  is  less  than  half  the  cost  of  an  equal  quantity 
of  nitrate  of  soda,  which  at  its  present  price  (235.  per 
cwt.)  may  be  reckoned  at  two-pence-halfpenny  a  pound, 
and  yet  it  may  be  shown,  that  a  given  weight  of  sulphate 
of  ammonia  contains  more  ammonia,  and  consequently 
ought  to  yield  more  nitrogen,  than  nitrate  of  soda.* 

"  Sulphate  of  ammonia  75  pis.  contain  of  ammonia  17  =  nitrogen  14. 

whilst 
Nitrate  of  soda  ....  86  pts 17= 14. 

**So  far  as  theory  goes,  therefore,  the  balance  would 
seem  to  be  in  favor  of  the  efficiency  of  sulphate  of  am- 
monia over  nitrate  of  soda,  in  the  proportion  of  15  to  86. 

''These  considerations  are  merely  offered,  by  way  of 
encouragement  to  those  who  may  be  disposed  to  make  trial 
of  this  promising  kind  of  manure,  and  of  course  will  go 
for  little  until  they  have  been  tested  by  experiment. 

''There  are  other  materials  also  employed  as  manure, 
which  appear  to  owe  their  efficacy  to  the  presence  of  am- 
monia, —  such,  for  example,  as  soot,  which  contains  a  con- 
siderable proportion  of  this  principle  united  with  carbonic 
acid,  and  which  accordingly  has  for  a  long  time  been  ad- 
vantageously employed  as  a  top-dressing  to  land. 

"Lastly,  the  foregoing  considerations  point  out  the  de- 
cided superiority  of  human  to  other  sorts  of  animal  manure. 

"  Independently  of  its  being  richer  in  most  of  those  in- 
gredients on  which  the  fertilizing  property  of  manure  de- 
pends, the  following  circumstance  gives  it  an  advantage. 

"  *  Nitrate  of  potass  ought  to  contain  ten  per  cent,  less  nitric  acid 
than  nitrate  of  soda,  but,  as  it  is  a  less  deliquescent  salt,  the  diiFerence 
between  the  two,  as  obtained  in  commerce,  is  not  very  considerable." 


PRACTICAL  INFERENCES.  285 

**  When  the  excrements  of  the  horse  or  ox  are  employed, 
we  are  obliged  to  allow  of  their  undergoing  a  long  previous 
process  of  fermentation,  by  which  a  large  proportion  of  their 
valuable  matter  is  got  rid  of,  in  order,  as  much  as  possible, 
to  destroy  the  vitality  of  the  seeds,  which  pass  undigested 
along  with  the  faeces.  And  after  all  many  still  remain, 
and  are  thus  introduced  into  the  fields  when  the  manure  is 
scattered  over  them. 

**By  the  use  of  night-soil  we  avoid  this  inconvenience, 
and  hence  it  is,  that  in  China,  where  it  is  exclusively  em- 
ployed, the  corn-fields  are  remarkably  exempt  from  weeds. 

**  Chemistry  has  suggested  means  for  destroying  those 
offensive  qualities  which  have  hitherto  limited  the  use  of 
this  species  of  manure,  although  it  is  stated  by  Liebig, 
that  the  method  adopted  for  that  purpose  on  the  Continent 
is  defective,  inasmuch  as  a  large  proportion  of  their  am- 
moniacal  contents  is  allowed  to  escape. 

**Even  under  its  present  management,  however,  the  pro- 
cess may  be  regarded  as  one  of  the  most  important  pres- 
ents which  chemistry  has  yet  made  to  the  practical  farmer, 
by  rendering  the  accumulated  filth  of  a  large  capital  avail- 
able for  his  purposes,  in  the  remotest  corner  of  the  British 
empire." 

Professor  Daubeny  concludes  his  lecture  with  some  high- 
ly ingenious  speculations  on  the  primary  source  of  the 
carbon  and  nitrogen  present  in  plants  and  animals.  He 
does  not  deem  it  probable  that  a  quantity  of  organic 
matter  was  called  into  existence  at  once,  sufficient  to  sup- 
ply the  whole  of  the  succeeding  races  of  plants  and  ani- 
mals with  these  ingredients  ;  or  that  the  whole,  which  is 
now  condensed  in  the  organization  of  the  animal  and  vege- 
table kingdoms,  was  at  any  one  time  present  in  the  atmo- 
sphere ;  but  that  the  carbon  and  nitrogen  of  plants  was 
originally  supplied  from  the  interior  of  the  earth  by  vol- 
canos.  The  fertility  of  the  neighborhood  of  Naples  Dr. 
D.  attributes  to  volcanic  exhalations. 

"Once  grant,"  he  continues,  '*  with  Liebig,  that  the 
nitrogen,  which  plants  possess,  can  only  be  obtained  by 
them  through  the  decomposition  of  ammonia,  and  it  will 
follow,  that  unless  this  gas  be  supplied  from  the  interior  of 
the  globe,  the  quantity  of  organic  matter,  into  which  this 
principle  enters  as  a  component  part,  will  be  undergoing 
a  continual  diminution. 

*'For  we  know  of  no  natural  processes  taking  place  on 
the  surface  of  the  globe,  which  generate   ammonia,  ex- 


286  APPExNDIX  TO  PART  I. 

cepting  those  connected  with  animal  and  vegetable  decompo- 
sition ;  whilst  there  are  many,  such  as  the  combustion  of 
various  organic  substances,  which,  by  resolving  bodies 
containing  nitrogen  into  their  constituent  elements,  would 
have  diminished  the  aggregate  amount  of  them  which  might 
have  formerly  existed. 

"  Some  compensating  process,  therefore,  is  clearly  re- 
quired, and  that,  if  I  mistake  not,  is  the  disengagement  of 
ammoniacal  gas  from  the  interior  of  the  globe." 

''Granting,  then,  what  upon  Liebig's  principles  seems 
most  consistent  with  analogy,  namely,  that  the  ammonia, 
no  less  than  the  carbonic  acid,  which  formed  the  food  of 
the  first  plants,  has  been  produced,  not  by  processes  of  ani- 
mal decay,  but  by  such  as  were  proceeding  within  the  globe 
prior  to  the  creation  of  living  beings,  the  notion  of  a  slow 
and  continuous  disengagement  of  both  compounds,  from  the 
earliest  period  to  the  present  time,  will  be  received  perhaps, 
as  at  least  the  most  probable  mode  of  accounting  for  their 
unfailing  supply. 

*'  Whilst  it  relieves  us  from  the  difficulty  of  supposing  the 
atmosphere  surcharged  with  these  gases  at  any  one  period, 
it  suggests  to  us,  at  the  same  time,  sublime  and  interesting 
views  of  the  arrangements  of  the  Deity,  in  thus  having  made 
all  things  subservient  to  one  common  end,  and  having  or- 
dained, that  the  mighty  agents  of  destruction,  which  exist 
in  the  bowels  of  the  earth,  should  minister,  like  the  malig- 
nant Genii  of  some  eastern  fable,  to  the  wants  and  necessities 
of  the  living  beings,  which  He  has  placed  upon  its  surface." 


USE    OF   PHOSPHATE    OF    SODA   IN   CALICO   PRINTING.* 

(See  page  186.) 

The  discovery  of  the  principle  which  led  to  the  use  of 
phosphate  of  soda,  was  made  in  the  United  States,  by  Dr. 
Dana,  of  Lowell.  The  first  practical  application  of  the 
salt  was  made,  in  consequence  of  Dr.  Dana's  researches, 
by  Mr.  J.  D.  Prince,  Jr.,  at  the  works  of  the  Merrimack 
Manufacturing  Company  in  Lowell,  in  1834.  Mr.  J.  D. 
Prince,  Sen.,  the  scientific  and  accomplished  superintend- 
ent of  the  establishment,  was  engaged  with  Dr.  Dana  for  a 

*  Substance  of  a  comrauQication  from  Dr.  Dana. 


DANIELL'S  ARTIFICIAL  MANURE.  287 

series  of  years  on  this  subject.  In  1839,  Mr.  Prince,  Jr. 
carried  the  process  to  England,  and,  with  Mr.  J.  Mercer  and 
Blyth,  took  out  letters  patent.  Mr.  Prince  sold  his  right  to 
Messrs.  Mercer  and  Blyth,  who  introduced  the  process  into 
the  establishments  on  the  Continent.  The  article  is  now 
made  by  M.  Kestner,  of  Thann,  who  observes,  in  his  letter 
to  the  '*Societe  Industrielle  de  Mulhouse,"  accompanying 
a  sample,  and  on  which  their  committee  reported.  Bulletin 
No.  63,  that  "the  article  is  the  invention  of  Messrs.  Mercer 
and  Blyth,  printers  of  calicoes  near  Manchester." 

Dr.  Liebig  probably  derived  his  knowledge  of  this  im- 
provement from  the  Bulletin  referred  to  above,  and  his 
statement  is  only  partial  respecting  the  effects  of  cow-dung. 
The  discovery  of  the  principle  of  its  action  has  led  to  the 
employment  of  other  salts,  which  produce  effects  equally 
good  as  phosphates. 


daniell's  artificial  manure.* 

The  basis  of  this  manure  is  wood  reduced  to  powder, 
sawdust,  which  is  to  be  thoroughly  saturated  with  bituminous 
and  animal  matters  of  all  or  any  kind  ;  to  this  is  to  be 
added  small  proportions  of  soda  and  quicklime.  The 
sample  exhibited  to  the  Royal  Agricultural  Society,  was  a 
coarse  black  powder,  having  a  strong  smell,  somewhat 
resembling  coal  tar.  In  England  its  price  will  be  about 
one  third  that  of  bone  dust.  It  is  a  kind  of  artificial 
bituminous  coal.  It  should  be  buried  two  or  three 
inches  under  the  surface  of  the  soil.  For  grass  land, 
it  is  to  be  well  mixed  with  a  considerable  portion  of 
ordinary  unvalued  mould.  The  quantity  to  be  used  will 
vary  with  the  crop.  About  twenty-four  bushels  per  acre 
are  recommended  for  wheat,  and  half  as  much  more, 
or  thirty-six  bushels,  may  be  carefully  applied  for  turnips 
or  mangel-wurtzel.  Its  direct  effect  is  thought  to  be  the 
conveyance  to  the  soil  of  the  direct  nutriment  of  future 
growth.  This  effect  is  produced  by  the  supply  of  ammo- 
nia to  the  soil  in  substances  calculated  to  retain  it  for  a 
time,  — to  again  absorb  it  from  the  atmosphere,  —  as  they 
give  it  out  to  plants  during  their  growth.  It  will  probably 
prevent  also  the  ravages  of  insects. 

*  Abridged  from  notices  in  the  New  Genesee  Farmer,  Vol.  III.,  by 
J.  E.  T.  , 


PART  II. 

OF  THE  CHEMICAL  PROCESSES  OF  FERMENTATION, 
DECAY,  AND  PUTREFACTION. 


CHAPTER  I. 

CHEMICAL  TRANSFORMATIONS. 

Woody  fibre,  sugar,  gum,  and  all  such  organic 
compounds,  suffer  certain  changes  when  in  contact 
with  other  bodies ;  that  is,  they  suffer  decomposition. 

There  are  two  distinct  modes  in  which  these  de- 
compositions take  place  in  organic  chemistry. 

When  a  substance  composed  of  two  compound 
bodies,  crystallized  oxalic  acid  for  example,  is  brought 
in  contact  with  concentrated  sulphuric  acid,  a  com- 
plete decomposition  is  effected  upon  the  application 
of  a  gentle  heat.  Now  crystallized  oxalic  acid  is  a 
combination  of  water  with  the  anhydrous  acid ;  but 
concentrated  sulphuric  acid  possesses  a  much  greater 
affinity  for  water  than  oxalic  acid,  so  that  it  attracts 
all  the  water  of  crystallization  from  that  substance. 
In  consequence  of  this  abstraction  of  the  water,  an- 
hydrous oxalic  acid  is  set  free ;  but  as  this  acid  can- 
not exist  in  a  free  state,  a  division  of  its  constitu- 
ents necessarily  ensues,  by  which  carbonic  acid  and 
carbonic  oxide  are  produced,  and  evolved  in  the 
gaseous  form  in  equal  volumes.  In  this  example, 
the  decomposition  is  the  consequence  of  the  removal 
of  two  constituents  (the  elements  of  water),  which 
unite  with  the  sulphuric  acid,  and  its  cause  is  the 
superior  affinity  of  the  acting  body  (the  sulphuric 
acid)  for  water.     In  consequence  of  the  removal  of 

25  #* 


290  CHEMICAL  TRANSFORMATIONS. 

the  component  parts  of  water,  the  remaining  ele- 
ments enter  into  a  new  form  ;  in  place  of  oxalic  acid, 
we  have  its  elements  in  the  form  of  carbonic  acid 
and  carbonic  oxide. 

This  form  of  decomposition,  in  which  the  change 
is  effected  by  the  agency  of  a  body  which  unites  with 
one  or  more  of  the  constituents  of  a  compound,  is 
quite  analogous  to  the  decomposition  of  inorganic 
substances.  When  we  bring  sulphuric  acid  and  ni- 
trate of  potash  together,  nitric  acid  is  separated  ia 
consequence  of  the  affinity  of  sulphuric  acid  for  pot- 
ash ;  in  consequence,  therefore,  of  the  formation  of 
a  new  compound  (sulphate  of  potash). 

In  the  second  form  of  these  decompositions,  the 
chemical  affinity  of  the  acting  body  causes  the  com- 
ponent parts  of  the  body  which  is  decomposed  to 
combine  so  as  to  form  new  compounds,  of  which 
either  both,  or  only  one,  combine  with  the  acting 
body.  Let  us  take  dry  w^ood,  for  example,  and  moist- 
en it  with  sulphuric  acid  ;  after  a  short  time  the  wood 
is  carbonized,  while  the  sulphuric  acid  remains  un- 
changed, with  the  exception  of  its  being  united  with 
more  water  than  it  possessed  before.  Now  this  wa- 
ter did  not  exist  as  such  in  the  wood,  although  its 
elements,  oxygen  and  hydrogen,  were  present ;  but 
by  the  chemical  attraction  of  sulphuric  acid  for  wa- 
ter, they  were  in  a  certain  measure  compelled  to 
unite  in  this  form ;  and  in  consequence  of  this,  the 
carbon  of  wood  was  separated  as  charcoal. 

Hydrocyanic  acid*  and  water,  in  contact  with  hy- 
drochloric acid,t  are  mutually  decomposed.  The 
nitrogen  of  the  hydrocyanic  acid,  and  a  certain  quan- 
tity of  the  hydrogen  of  the  water,  unite  together  and 
form  ammonia;  whilst  the  carbon  and  hydrogen  of 
the  hydrocyanic  acid  combine  with  the  oxygen  of  the 
water,  and  form  formic  acid.  {     The   ammonia  com- 

*  See  page  70,  note. 

t  Formerly  called  Muriatic  Acid,  obtained  from  sea  salt  and  compos* 
ed  of  Hydrogen  and  Chlorine  in  equal  vols.  H  -j-  CI. 
X  See  page  70. 


EXAMPLES.  291 

bines  with  the  muriatic  acid.  Here  the  contact  of 
muriatic  acid  with  water  and  hydrocyanic  acid  caus- 
es a  disturbance  in  the  attraction  of  the  elements  of 
both  compounds,  in  consequence  of  which  they  ar- 
range themselves  into  new  combinations,  one  of 
which,  —  ammonia,  —  possesses  the  power  of  uniting 
with  the  acting  body. 

Inorganic  chemistry  can  present  instances  analo- 
gous to  this  iclass  of  decomposition  also ;  but  there 
are  forms  of  organic  chemical  decomposition  of  a 
very  different  kind,  in  which  none  of  the  component 
parts  of  the  matter  which  suffers  decomposition  enter 
into  combination  with  the  body  which  determines  the 
decomposition.  In  cases  of  this  kind  a  disturbance 
is  produced  in  the  mutual  attraction  of  the  elements 
of  a  compound,  and  they  in  consequence  arrange 
themselves  into  one  or  several  new  combinations, 
which  are  incapable  of  suffering  further  change  under 
the  same  conditions. 

When,  by  means  of  the  chemical  affinity  of  a  sec- 
ond body,  by  the  influence  of  heat,  or  through  any 
other  causes,  the  composition  of  an  organic  compound 
is  made  to  undergo  such  a  change,  that  its  elements 
form  two  or  more  new  compounds,  this  manner  of 
decomposition  is  called  a  chemical  transformation  or 
metamorphosis,  '  It  is  an  essential  character  of  chem- 
ical transformations,  that  none  of  the  elements  of  the 
body  decomposed  are  singly  set  at  liberty. 

The  changes,  which  are  designated  by  the  terms 
fermentation,  decay,  and  putrefaction,  are  chemical 
transformations  effected  by  an  agency  which  has 
hitherto  escaped  attention,  but  the  existence  of 
which  will  be  proved  in  the  following  pages. 


292  CHEMICAL  TRANSFORMATIONS. 


CHAPTER   11. 

ON  THE  CAUSES  WHICH  EFFECT  FERMENTATION;  DECAY,* 

AND  PUTREFACTION. 

Attention  has  been  recently  directed  to  the  fact, 
that  a  body  in  the  act  of  combination  of  decomposi- 
tion exercises  an  influence  upon  any  other  body  with 
which  it  may  be  in  contact.  Platinum,  for  example, 
does  not  decompose  nitric  acid ;  it  may  be  boiled 
with  this  acid  without  being  oxidized  by  it,  even 
when  in  a  state  of  such  fine  division,  that  it  no  long- 
er reflects  light  (black  spongy  platinum).  But  an 
alloy  of  silver  and  platinum  dissolves  with  great  ease 
in  nitric  acid;  the  oxidation  which  the  silver  suffers, 
causes  the  platinum  to  submit  to  the  same  change  ; 
or,  in  other  words,  the  latter  body,  from  its  contact 
with  the  oxidizing  silver,  acquires  the  property  of 
decomposing  nitric  acid. 

Copper  does  not  decompose  water,  even  when 
boiled  in  dilute  sulphuric  acid ;  but  an  alloy  of  cop- 
per, zinc,  and  nickel,  dissolves  easily  in  this  acid 
with  evolution  of  hydrogen  gas. 

Tin  decomposes  nitric  acid  with  great  facility,  but 
water  with  difficulty  ;  and  yet,  when  tin  is  dissolved 
in  nitric  acid,  hydrogen  is  evolved  at  the  same  time, 
from  a  decomposition  of  the  water  contained  in  the 
acid,  and  ammonia  is  formed  in  addition  to  oxide 
of  tin. 

In  the  examples  here  given,  the  only  combination 
or  decomposition  which  can  be  explained  by  chemi- 
cal affinity  is  the  last.     In  the  other  cases,  electrical 

*  An  essential  distinction  is  drawn  in  the  following  part  of  the  work, 
between  decay  and  'putrefaction  {Verwesung  und  Fdvlniss)^  and  they  are 
shown  to  depend  on  different  causes  ;  but  as  the  word  decay  is  not  gen- 
erally applied  to  a  distinct  species  of  decomposition,  and  does  not  indi- 
cate its  true  nature,  I  shall  in  future,  at  the  suggestion  of  the  author, 
employ  the  term  eremacausis,  the  meaning  of  which  has  been  already 
explained.  —  Ed. 


THEIR  CAUSES.  293 

action  ought  to  have  retarded  or  prevented  the  oxi- 
dation of  the  platinum  or  copper  while  they  were  in 
contact  with  silver  or  zinc,  but,  as  experience  shows, 
the  influence  of  the  opposite  electrical  conditions  is 
more  than  counterbalanced  by  chemical  actions. 

The  same  phenomena  are  seen  in  a  less  dubious 
form  in  compounds,  the  elements  of  w^hich  are  held 
together  only  by  a  feeble  affinity.  It  is  well  known, 
that  there  are  chemical  compounds  of  so  unstable  a 
nature,  that  changes  in  temperature  and  electrical 
condition,  or  even  simple  mechanical  friction,  or  con- 
tact with  bodies  of  apparently  totally  indifferent  na- 
tures, cause  such  a  disturbance  in  the  attraction  of 
their  constituents,  that  the  latter  enter  into  new 
forms,  without  any  of  them  combining  with  the  act- 
ing body.  These  compounds  appear  to  stand  but 
just  within  the  limits  of  chemical  combination,  and 
agents  exercise  a  powerful  influence  on  them,  which 
are  completely  devoid  of  action  on  compounds  of  a 
stronger  affinity.  Thus,  by  a  slight  increase  of  tem- 
perature, the  elements  of  hypochlorous  acid*  sep- 
arate from  one  another  with  evolution  of  heat  and 
light ;  chloride  of  nitrogen  explodes  by  contact  with 
many  bodies,  which  combine  neither  with  chlorine 
nor  nitrogen  at  common  temperatures ;  and  the  con- 
tact of  any  solid  substance  is  sufficient  to  cause  the 
explosion  of  iodide  of  nitrogen,  or  fulminating  silver. 

It  has  never  been  supposed  that  the  causes  of  the 
decomposition  of  these  bodies  should  be  ascribed  to 
a  peculiar  power,  different  from  that  which  regulates 
chemical  affinity,  —  a  power  which  mere  contact  with 
the  down  of  a  feather  is  sufficient  to  set  in  activity, 
and  which,  once  in  action,  gives  rise  to  the  decom- 
position. These  substances  have  always  been  viewed 
as  chemical  compounds  of  a  very  unstable  nature,  in 
which  the  component  parts  are  in  a  state  of  such 
tension,  that  the  least  disturbance  overcomes  their 
chemical  affinity.     They  exist  only  by  the  vis  inerticn^ 

*  Formerly,  protoxide  of  chlorine. 

25* 


294  CHEMICAL  TRANSFORMATIONS.  M 

and  any  shock  or  movement  is  sufficient  to  destroy 
the  attraction  of  their  component  parts,  and  conse- 
quently their  existence  in  their  definite  form. 

Peroxide  of  hydrogen*  belongs  to  this  class  of 
bodies ;  it  is  decomposed  by  all  substances  capable 
of  attracting  oxygen  from  it,  and  even  by  contact 
with  many  bodies,  such  as  platinum  or  silver,  which 
do  not  enter  into  combination  with  any  of  its  con- 
stituents. In  this  respect,  its  decomposition  depends 
evidently  upon  the  same  causes  which  effect  that  of 
iodide  of  nitrogen,  or  fulminating  silver.  Yet  it  is 
singular,  that  the  cause  of  the  sudden  separation  of 
the  component  parts  of  peroxide  of  hydrogen  has 
been  viewed  as  different  from  those  of  common  de- 
composition, and  has  been  ascribed  to  a  new  power 
termed  the  catalytic  force.  Now,  it  has  not  been  con- 
sidered, that  the  presence  of  the  platinum  and  silver 
serves  here  only  to  accelerate  the  decomposition ; 
for  without  the  contact  of  these  metals,  the  peroxide 
of  hydrogen  decomposes  spontaneously,  although 
very  slowly.  The  sudden  separation  of  the  constit- 
uents of  peroxide  of  hydrogen  differs  from  the  de- 
composition of  gaseous  hypochlorous  acid,  or  solid 
iodide  of  nitrogen,  only  in  so  far  as  the  decomposi- 
tion takes  place  in  a  liquid. 

A  remarkable  action  of  peroxide  of  hydrogen  has 
attracted  much  attention,  because  it  differs  from 
ordinary  chemical  phenomena.  This  is  the  reduction 
which  certain  oxides  suffer  by  contact  with  this  sub- 
stance, on  the  instant  at  which  the  oxygen  separates 
from  the  water.  The  oxides  thus  easily  reduced, 
are  those  of  which  the  whole,  or  part  at  least,  of 
their  oxygen  is  retained  merely  by  a  feeble  affinity, 
such  as  the  oxides  of  silver  and  of  gold,  and  perox- 
ide of  lead. 

Now,  other  oxides,  which  are  very  stable  in  com- 
position, effect  the  decomposition  of  peroxide  of  hy- 

*  A  remarkable  compound,  consisting  of  1  Hydrogen,  and  2  Oxygen. 
See  description  and  process  for  obtaining;  in  Webster's  Chemistry f 
p.  134. 


THEIR  CAUSE.  295 

drogen,  without  experiencing  the  smallest  change ; 
but  when  oxide  of  silver  is  employed  to  effect 
the  decomposition,  all  the  oxygen  of  the  silver  is 
carried  away  with  that  evolved  from  the  peroxide 
of  hydrogen,  and,  as  a  result  of  the  decomposition, 
water  and  metallic  silver  remain.  When  peroxide 
of  lead  ^  is  used  for  the  same  purpose,  half  its  oxy- 
gen escapes  as  a  gas.  Peroxide  of  manganese  may 
in  the  same  manner  be  reduced  to  the  protoxide,  and 
ogygen  set  at  liberty,  if  an  acid  is  at  the  same  time 
present,  which  will  exercise  an  affinity  for  the  pro- 
toxide and  convert  it  into  a  soluble  salt.  If,  for  ex- 
ample, we  add  to  peroxide  of  hydrogen  sulphuric 
acid,  and  then  peroxide  of  manganese  in  the  state  of 
fine  powder,  much  more  oxygen  is  evolved  than  the 
compound  of  oxygen  and  hydrogen  could  yield  ;  and 
if  we  examine  the  solution  which  remains,  we  find  a 
salt  of  the  protoxide  of  manganese,  so  that  half  of 
the  oxygen  has  been  evolved  from  the  peroxide  of 
that  metal. 

A  similar  phenomenon  occurs,  when  carbonate  of 
silver  is  treated  with  several  organic  acids.  Pyruvic 
acid,  for  example,  combines  readily  with  pure  oxide 
of  silver,  and  forms  a  salt  of  sparing  solubility  in 
water.  But  when  this  acid  is  brought  in  contact 
with  carbonate  of  silver,  the  oxygen  of  part  of  the 
oxide  escapes  with  the  carbonic  acid,  and  metal- 
lic silver  remains  in  the  state  of  a  black  powder. 
(Berzelius.) 

Now  no  other  explanation  of  these  phenomena 
can  be  given,  than  that  a  body  in  the  act  of  com- 
bination or  decomposition  enables  another  body,  with 
which  it  is  in  contact,  to  enter  into  the  same  state. 
It  is  evident  that  the  active  state  of  the  atoms  of  one 
body  has  an  influence  upon  the  atoms  of  a  body  in 
contact  with  it ;  and  if  these  atoms  are  capable  of 
the  same  change  as  the  former,  they  likewise  under- 

*  A  peroxide  is  one  that  contains  the  largest  proportion  of  oxygen. 
When  several  compounds  of  metals  and  oxygen  occur,  that  which  con- 
tains the  smallest  proportion  of  oxygen  is  called  the  first  or  protoxide. 


296  CHEMICAL  TRANSFORMATIONS. 

go  that  change;  and  combinations  and  decompo- 
sitions are  the  consequence.  But  when  the  atoms 
of  the  second  body  are  not  capable  of  such  an  action, 
any  further  disposition  to  change  ceases  from  the 
moment  at  which  the  atoms  of  the  first  body  assume 
the  state  of  rest,  that  is,  when  the  changes  or  trans- 
formations of  this  body  are  quite  completed. 

This  influence  exerted  by  one  compound  upon  the 
other,  is  exactly  similar  to  that  which  a  body  in  the 
act  of  combustion  exercises  upon  a  combustible  body 
in  its  vicinity ;  with  this  difference  only,  that  the 
causes  which  determine  the  participation  and  dura- 
tion of  these  conditions  are  different.  For  the  cause, 
in  the  case  of  the  combustible  body,  is  heat,  which 
is  generated  every  moment  anew ;  whilst  in  the  phe- 
nomena of  decomposition  and  combination  which  we 
are  considering  at  present,  the  cause  is  a  body  in 
the  state  of  chemical  action,  which  exerts  the  de- 
composing influence  only  so  long  as  this  action 
continues. 

Numerous  facts  show,  that  motion  alone  exercises 
a  considerable  influence  on  chemical  forces.  Thus, 
the  power  of  cohesion  does  not  act  in  many  saline 
solutions,  even  when  they  are  fully  saturated  with 
salts,  if  they  are  permitted  to  cool  whilst  at  rest. 
In  such  a  case,  the  salt  dissolved  in  a  liquid  does  not 
crystallize;  but  when  a  grain  of  sand  is  thrown  into 
the  solution,  or  when  it  receives  the  slightest  move- 
ment, the  whole  liquid  becomes  suddenly  solid  while 
heat  is  evolved.  The  same  phenomenon  happens 
with  water,  for  this  liquid  may  be  cooled  much  under 
32^  F.  (0°  C),  if  kept  completely  undisturbed,  but 
solidifies  in  a  moment  when  put  in  motion. 

The  atoms  of  a  body  must  in  fact  be  set  in  motion 
before  they  can  overcome  the  vis  inertim  so  as  to  ar- 
range themselves  into  certain  forms.  A  dilute  solution 
of  a  salt  of  potash  mixed  with  tartaric  acid  yields  no 
precipitate  whilst  at  rest ;  but  if  motion  is  communi- 
cated to  the  solution  by  agitating  it  briskly,  solid 
crystals  of  cream  of  tartar  are  deposited.     A  solu- 


FERMENTATION  AND  PUTREFACTION.  297 

tion  of  a  salt  of  magnesia,  also,  which  is  not  rendered 
turbid  by  the  addition  of  phosphate  of  ammonia,  de- 
posits the  phosphate  of  magnesia  and  ammonia  on 
those  parts  of  the  vessel  touched  with  the  rod  em- 
ployed in  stirring. 

In  the  processes  of  combination  and  decompo- 
sition under  consideration,  motion,  by  overcoming 
the  vis  inerticB,  gives  rise  immediately  to  another 
arrangement  of  the  atoms  of  a  body,  that  is,  to  the 
production  of  a  compound  which  did  not  before 
exist  in  it.  Of  course  these  atoms  must  previously 
possess  the  power  of  arranging  themselves  in  a  cer- 
tain order,  otherwise  both  friction  and  motion  would 
be  without  the  smallest  influence. 

The  simple  permanence  in  position  of  the  atoms 
of  a  body,  is  the  reason  that  so  many  compounds  ap- 
pear to  present  themselves,  in  conditions,  and  with 
properties,  different  from  those  which  they  possess, 
when  they  obey  the  natural  attractions  of  their  atoms. 
Thus  sugar  and  glass,  when  melted  and  cooled  rapid- 
ly, are  transparent,  of  a  conchoidal  fracture,  and 
elastic  and  flexible  to  a  certain  degree.  But  the 
former  becomes  dull  and  opaque  on  keeping,  and 
exhibits  crystalline  faces  by  cleavage,  which  belong 
to  crystallized  sugar.  Glass  assumes  also  the  same 
condition,  when  kept  soft  by  heat  for  a  long  period ; 
it  becomes  white,  opaque,  and  so  hard  as  to  strike 
fire  with  steel.  Now,  in  both  these  bodies,  the  com- 
pound molecules  evidently  have  different  positions 
in  the  two  forms.  In  the  first  form  their  attraction 
did  not  act  in  the  direction  in  which  their  power  of 
cohesion  was  strongest.  It  is  known,  also,  that  when 
sulphur  is  melted  and  cooled  rapidly  by  throwing  it 
into  cold  water,  it  remains  transparent,  elastic,  and 
so  soft  that  it  may  be  drawn  out  into  long  threads ; 
but  that  after  a  few  hours  or  days,  it  becomes  again 
hard  and  crystalline. 

The  remarkable  fact  here  is,  that  the  amorphous 
sugar  or  sulphur  returns  again  into  the  crystalline 
condition,  without  any  assistance  from  an  exterior 


298  CHEMICAL  TRANSFORMATIONS. 

cause ;  a  fact  which  shows,  that  their  molecules  have 
assumed  another  position,  and  that  they  possess, 
therefore,  a  certain  degree  of  mobility,  even  in  the 
condition  of  a  solid.  A  very  rapid  transposition  or 
transformation  of  this  kind  is  seen  in  arragonite,  a 
mineral  which  possesses  exactly  the  same  compo- 
sition as  calcareous  spar,  but  of  which  the  hardness 
and  crystalline  form  prove  that  its  molecules  are 
arranged  in  a  different  manner.  When  a  crystal  of 
arragonite  is  heated,  an  interior  motion  of  its  mole- 
cules is  caused  by  the  expansion ;  the  permanence 
of  their  arrangement  is  destroyed ;  and  the  crystal 
splinters  with  much  violence,  and  falls  into  a  heap 
of  small  crystals  of  calcareous  spar. 

It  is  impossible  for  us  to  be  deceived  regarding  the 
causes  of  these  changes.  They  are  owing  to  a  dis- 
turbance of  the  state  of  the  equilibrium,  in  con- 
sequence of  which  the  particles  of  the  body  put  in 
motion  obey  other  affinities  or  their  own  natural 
attractions. 

But  if  it  is  true,  as  we  have  just  shown  it  to  be, 
that  mechanical  motion  is  sufficient  to  cause  a  change 
of  condition  in  many  bodies,  it  cannot  be  doubted 
that  a  body  in  the  act  of  combination  or  decompo- 
sition is  capable  of  imparting  the  same  condition  of 
motion  or  activity  in  which  its  atoms  are  to  certain 
other  bodies  :  or  in  other  words,  to  enable  other 
bodies  with  which  it  is  in  contact  to  enter  into  com- 
binations, or  suffer  decompositions. 

The  reality  of  this  influence  has  been  already  suffi- 
ciently proved  by  the  facts  derived  from  inorganic 
chemistry,  but  it  is  of  much  more  frequent  occurrence 
in  the  relations  of  organic  matter,  and  causes  very 
striking  and  wonderful  phenomena. 

By  the  terms  fermentation y  putrefaction,  and  erema^ 
causiSy  are  meant  those  changes  in  form  and  prop- 
erties which  compound  organic  substances  undergo 
when  separated  from  the  organism,  and  exposed  to 
the  influence  of  water  and  a  certain  temperature. 
Fermentation  and  putrefaction  are  examples  of  that 


FERMENTATION  AND  PUTREFACTION.  299 

kind  of  decomposition,  which  we  have  named  trans- 
formations :  the  elements  of  the  bodies  capable  of 
undergoing  these  changes  arrange  themselves  into 
new  combinations,  in  which  the  constituents  of  water 
generally  take  a  part. 

Eremacansis  (or  decay)  differs  from  fermentation 
and  putrefaction,  inasmuch  as  it  cannot  take  place 
without  the  access  of  air,  the  oxygen  of  which  is 
absorbed  by  the  decaying  bodies.  Hence,  it  is  a 
process  of  slow  combustion,  in  which  heat  is  uni- 
formly evolved,  and  occasionally  even  light.  In  the 
processes  of  decomposition  termed  fermentation  and 
putrefaction,  gaseous  products  are  very  frequently 
formed,  which  are  either  inodorous,  or  possess  a  very 
offensive  smell. 

The  transformations  of  those  matters  which  evolve 
gaseous  products  without  odor,  are  now,  by  pretty 
general  consent,  designated  by  the  term  fermenta- 
tion;  whilst  to  the  spontaneous  decomposition  of 
bodies  which  emit  gases  of  a  disagreeable  smell,  the 
term  putrefaction  is  applied.  But  the  smell  is  of 
course  no  distinctive  character  of  the  nature  of  the 
decomposition,  for  both  fermentation  and  putrefac- 
tion are  processes  of  decomposition  of  a  similar  kind, 
the  one  of  substances  destitute  of  nitrogen,  the  oth- 
er of  substances  which  contain  it. 

It  has  also  been  customary  to  distinguish  from 
fermentation  and  putrefaction  a  particular  class  of 
transformations,  viz.,  those  in  which  conversions  and 
transpositions  are  effected  without  the  evolution  of 
gaseous  products.  But  the  conditions  under  which 
the  products  of  the  decomposition  present  them- 
selves are  purely  accidental ;  there  is,  therefore,  no 
reason  for  the  distinction  just  mentioned. 


298  CHEMICAL  TRANSFORMATIONS. 

cause ;  a  fact  which  shows,  that  their  molecules  have 
assumed  another  position,  and  that  they  possess, 
therefore,  a  certain  degree  of  mobility,  even  in  the 
condition  of  a  solid.  A  very  rapid  transposition  or 
transformation  of  this  kind  is  seen  in  arragonite,  a 
mineral  which  possesses  exactly  the  same  compo- 
sition as  calcareous  spar,  but  of  which  the  hardness 
and  crystalline  form  prove  that  its  molecules  are 
arranged  in  a  different  manner.  When  a  crystal  of 
arragonite  is  heated,  an  interior  motion  of  its  mole- 
cules is  caused  by  the  expansion ;  the  permanence 
of  their  arrangement  is  destroyed ;  and  the  crystal 
splinters  with  much  violence,  and  falls  into  a  heap 
of  small  crystals  of  calcareous  spar. 

It  is  impossible  for  us  to  be  deceived  regarding  the 
causes  of  these  changes.  They  are  owing  to  a  dis- 
turbance of  the  state  of  the  equilibrium,  in  con- 
sequence of  which  the  particles  of  the  body  put  in 
motion  obey  other  affinities  or  their  own  natural 
attractions. 

But  if  it  is  true,  as  we  have  just  shown  it  to  be, 
that  mechanical  motion  is  sufficient  to  cause  a  change 
of  condition  in  many  bodies,  it  cannot  be  doubted 
that  a  body  in  the  act  of  combination  or  decompo- 
sition is  capable  of  imparting  the  same  condition  of 
motion  or  activity  in  which  its  atoms  are  to  certain 
other  bodies  :  or  in  other  words,  to  enable  other 
bodies  with  which  it  is  in  contact  to  enter  into  com- 
binations, or  suffer  decompositions. 

The  reality  of  this  influence  has  been  already  suffi- 
ciently proved  by  the  facts  derived  from  inorganic 
chemistry,  but  it  is  of  much  more  frequent  occurrence 
in  the  relations  of  organic  matter,  and  causes  very 
striking  and  wonderful  phenomena. 

By  the  iitvms  fermentation y  putrefaction^  and  erema- 
causis,  are  meant  those  changes  in  form  and  prop- 
erties which  compound  organic  substances  undergo 
when  separated  from  the  organism,  and  exposed  to 
the  influence  of  water  and  a  certain  temperature. 
Fermentation  and  putrefaction  are  examples  of  that 


FERMENTATION  AND  PUTREFACTION.  299 

kind  of  decomposition,  which  we  have  named  trans- 
formations :  the  elements  of  the  bodies  capable  of 
undergoing  these  changes  arrange  themselves  into 
new  combinations,  in  which  the  constituents  of  water 
generally  take  a  part. 

Eremacansis  (or  decay)  differs  from  fermentation 
and  putrefaction,  inasmuch  as  it  cannot  take  place 
without  the  access  of  air,  the  oxygen  of  which  is 
absorbed  by  the  decaying  bodies.  Hence,  it  is  a 
process  of  slow  combustion,  in  which  heat  is  uni- 
formly evolved,  and  occasionally  even  light.  In  the 
processes  of  decomposition  termed  fermentation  and 
putrefaction,  gaseous  products  are  very  frequently 
formed,  which  are  either  inodorous,  or  possess  a  very 
offensive  smell. 

The  transformations  of  those  matters  which  evolve 
gaseous  products  without  odor,  are  now,  by  pretty 
general  consent,  designated  by  the  term  fermenta- 
Hon;  whilst  to  the  spontaneous  decomposition  of 
bodies  which  emit  gases  of  a  disagreeable  smell,  the 
term  putrefaction  is  applied.  But  the  smell  is  of 
course  no  distinctive  character  of  the  nature  of  the 
decomposition,  for  both  fermentation  and  putrefac- 
tion are  processes  of  decomposition  of  a  similar  kind, 
the  one  of  substances  destitute  of  nitrogen,  the  oth- 
er of  substances  which  contain  it. 

It  has  also  been  customary  to  distinguish  from 
fermentation  and  putrefaction  a  particular  class  of 
transformations,  viz.,  those  in  which  conversions  and 
transpositions  are  effected  without  the  evolution  of 
gaseous  products.  But  the  conditions  under  which 
the  products  of  the  decomposition  present  them- 
selves are  purely  accidental ;  there  is,  therefore,  no 
reason  for  the  distinction  just  mentioned. 


300  CHEMICAL  TRANSFOKMATIONS. 


CHAPTER   III. 

FERMENTATION  AND  PUTREFACTION. 

Several  bodies  appear  to  enter  spontaneously  into 
the  states  of  fermentation  and  putrefaction,  particu- 
larly such  as  contain  nitrogen  or  azotized  substan- 
ces. N0W5  it  is  very  remarkable,  that  very  small- 
quantities  of  these  substances,  in  a  state  of  fermenta- 
tion or  putrefaction,  possess  the  power  of  causing 
unlimited  quantities  of  similar  matters  to  pass  into 
the  same  state.  Thus,  a  small  quantity  of  the  juice 
of  grapes  in  the  act  of  fermentation,  added  to  a 
large  quantity  of  the  same  fluid,  which  does  not  fer- 
ment, induces  the  state  of  fermentation  in  the  whole 
mass.  So  likewise  the  most  minute  portion  of  milk, 
paste,  juice  of  the  beet-root,  flesh,  or  blood,  in  the 
state  of  putrefaction,  causes  fresh  milk,  paste,  juice 
of  the  beet-root,  flesh,  or  blood,  to  pass  into  the 
same  condition  when  in  contact  with  them. 

These  changes  evidently  differ  from  the  class  of 
common  decompositions  which  are  effected  by  chem- 
ical affinity ;  they  are  chemical  actions,  conversions, 
or  decompositions,  excited  by  contact  with  bodies 
already  in  the  same  condition.  In  order  to  form  a 
clear  idea  of  these  processes,  analogous  and  less 
complicated  phenomena  must  previously  be  studied. 

The  compound  nature  of  the  molecules  of  an  or- 
ganic body,  and  the  phenomena  presented  by  them 
when  in  relation  with  other  matters,  point  out  the 
true  cause  of  these  transformations.  Evidence  is 
afforded  even  by  simple  bodies,  that  in  the  formation 
of  combinations,  the  force  with  which  the  combining 
elements  adhere  to  one  another  is  inversely  propor- 
tional to  the  number  of  simple  atoms  in  the  com- 
pound molecule.  Thus,  protoxide  of  manganese  by 
absorption  of  oxygen  is  converted  into  the  sesqui- 
oxide,  the  peroxide,  manganic,  and  hypermanganic 


OF  ORGANIC  COMPOUNDS.  301 

acids,  the  number  of  atoms  of  oxygen  being  aug- 
mented by  I,  by  1,  by  2,  and  by  5.  But  all  the 
oxygen  contained  in  these  compounds,  beyond  that 
which  belongs  to  the  protoxide,  is  bound  to  the 
manganese  by  a  much  morfe  feeble  affinity ;  a  red 
heat  causes  an  evolution  of  oxygen  from  the  per- 
oxide, and  the  manganic  and  hypermanganic  acids 
cannot  be  separated  from  their  bases  without  under- 
going immediate  decomposition. 

There  are  many  facts  which  prove,  that  the  most 
simple  inorganic  compounds  are  also  the  most  stable, 
and  undergo  decomposition  with  the  greatest  diffi- 
culty, whilst  those  which  are  of  a  complex  composi- 
tion yield  easily  to  changes  and  decompositions. 
The  cause  of  this  evidently^is,  that,  in  proportion  to 
the  number  of  atoms  which  enter  into  a  compound, 
the  directions  in  which  their  attractions  act  will  be 
more  numerous. 

Whatever  ideas  we  may  entertain  regarding  the 
infinite  divisibility  of  matter  in  general,  the  exist- 
ence of  chemical  proportions  removes  every  doubt 
respecting  the  presence  of  certain  limited  groups  or 
masses  of  matter  which  we  have  not  the  power  of 
dividing.  The  particles  of  matter  called  equivalents 
in  chemistry  are  not  infinitely  small,  for  they  possess 
a  weight,  and  are  capable  of  arranging  themselves 
in  the  most  various  ways,  and  of  thus  forming 
innumerable  compound  atoms.  The  properties  of 
these  compound  atoms  differ  in  organic  nature,  not 
only  according  to  the  form,  but  also  in  many  instan- 
ces according  to  the  direction  and  place,  which  the 
simple  atoms  take  in  the  compound  molecules. 

When  we  compare  the  composition  of  organic 
compounds  with  inorganic,  we  are  quite  amazed  at 
the  existence  of  combinations,  in  one  single  molecule 
of  which,  ninety  or  several  hundred  atoms  or  equiv- 
alents are  united.  Thus,  the  compound  atom  of  an 
organic  acid  of  very  simple  composition,  acetic  acid, 
for  example,  contains  twelve  equivalents  of  simple 
elements;  one  atom  of  kinovic  acid  contains  33,  1 
26       . 


302  CHEMICAL  TRANSFORMATIONS. 

of  sugar  36,  1  of  amygdalin  90,  and  1  of  stearic 
acid  138  equivalents.  The  component  parts  of 
animal  bodies  are  infinitely  more  complex  even  than 
these. 

Inorganic  compounds  differ  from  organic  in  as 
great  a  degree  in  their  other  characters  as  in  their 
simplicity  of  constitution.  Thus,  the  decomposition 
of  a  compound  atom  of  sulphate  of  potash  is  aided 
by  numerous  causes,  such  as  the  power  of  cohesion, 
or  the  capability  of  its  constituents  to  form  solid; 
insoluble,  or  at  certain  temperatures  volatile  com- 
pounds with  the  body  brought  into  contact  with  it, 
and  nevertheless  a  vast  number  of  other  substances 
produce  in  it  not  the  slightest  change.  Now^,  in  the 
decomposition  of  a  coirf][)lex  organic  atom,  there  is 
nothing  similar  to  this. 

The  empirical  formula  of  sulphate  of  potash  is 
SKO4.*  It  contains  only  1  eq.  of  sulphur,  and  1  eq. 
of  potassium.  We  may  suppose  the  oxygen  to  be 
differently  distributed  in  the  compound,  and  by  a 
decomposition  we  may  remove  a  part  or  all  of  it,  or 
replace  one  of  the  constituents  of  the  compound  by 
another  substance.  But  w^e  cannot  produce  a  differ- 
ent arrangement  of  the  atoms,  because  they  are 
already  disposed  in  the  simplest  form  in  which  it  is 
possible  for  them  to  combine.  Now,  let  us  compare 
the  composition  of  sugar  of  grapes  with  the  above  : 
here  12  eq.  of  carbon,  12  eq.  of  hydrogen,  and  12  eq. 
of  oxygen,  are  united  together,  and  we  know  that 
they  are  capable  of  combining  with  each  other  in 
the  most  various  ways.  From  the  formula  of  sugar, 
we  might  consider  it  either  as  a  hydrate  of  carbon, 
wood,  starch,  or  sugar  of  milk,  or  further,  as  a  com- 
pound of  ether  with  alcohol  or  of  formic  acid  with 
sachulmin.f  Indeed,  we  may  calculate  almost  all 
the  known  organic  compounds  destitute  of  nitrogen 

*  S  denotes  sulphur,  K  (Kali)  potash,  O  oxygen,  4  the  number  of 
atoms.     When  no  number  is  used,  one  atom  is  understood. 

i  The  black  precipitate  obtained  by  the  action  of  hydrochloric  acid 
on  sugar. 


OF  ORGANIC  COMPOUNDS-  303 

I  from  sugar,  by  simply  adding  the  elements  of  water, 
I  or  by  replacing  any  one  of  its  elementary  constitu- 
!  ents  by  a  different  substance.  The  elements  neces- 
sary to  form  these  compounds  are,  therefore,  con- 
tained in  the  sugar,  and  they  must  also  possess  the 
power  of  forming  numerous  combinations  amongst 
themselves  by  their  mutual  attractions. 

Now,  when  we  examine  what  changes  sugar  under- 
goes when  brought  into  contact  with  other  bodies 
which  exercise  a  marked  influence  upon  it,  we  find, 
that  these  changes  are  not  confined  to  any  narrow 
limits,  like  those  of  inorganic  bodies,  but  are  in  fact 
unlimited. 

The  elements  of  sugar  yield  to  every  attraction, 
and  to  each  in  a  peculiar  manner.  In  inorganic 
compounds,  an  acid  acts  upon  a  particular  constitu- 
ent of  the  body,  which  it  decomposes,  by  virtue  of 
its  affinity  for  that  constituent,  and  never  resigns  its 
proper  chemical  character,  in  whatever  form  it  may 
be  applied.  But  when  it  acts  upon  sugar,  and 
induces  great  changes  in  that  compound,  it  does 
this  not  by  any  superior  affinity  for  a  base  existing 
in  the  sugar,  but  by  disturbing  the  equilibrium  in  the 
mutual  attraction  of  the  elements  of  the  sugar 
amongst  themselves.  Muriatic  and  sulphuric  acids, 
which  differ  so  much  from  one  another  both  in  char- 
acters and  composition,  act  in  the  same  manner  upon 
sugar.  But  the  action  of  both  varies  according  to  the 
state  in  which  they  are ;  thus  they  act  in  one  way 
when  dilute,  in  another  when  concentrated,  and  even 
differences  in  their  temperature  cause  a  change  in 
their  action.  Thus  sulphuric  acid  of  a  moderate 
degree  of  concentration  converts  sugar  into  a  black 
carbonaceous  matter,  forming  at  the  same  time  acetic 
and  formic  acids.  But  when  the  acid  is  more  diluted, 
the  sugar  is  converted  into  two  brown  substances, 
both  of  them  containing  carbon  and  the  elements  of 
water.  Again,  when  sugar  is  subjected  to  the  action 
of  alkalies,  a  whole  series  of  different  new  products 
is  obtained ;  while  oxidizing  agents,  such  as  nitric 


f 


304  CHEMICAL  TRANSFORMATIONS 

acid,  produce  from  it  carbonic  acid,  acetic  acid,  oxalic 
acid,  formic  acid,  and  many  other  products  which 
have  not  yet  been  examined. 

If,  from  the  facts  here  stated,  we  estimate  the 
power  with  which  the  elements  of  sugar  are  united 
together,  and  judge  of  the  force  of  their  attraction 
by  the  resistance  which  they  offer  to  the  action  of 
bodies  brought  into  contact  with  them,  we  must 
regard  the  atom  of  sugar  as  belonging  to  that  class 
of  compound  atoms,  which  exist  only  by  the  vis- 
inerticB  of  their  elements.  Its  elements  seem  merely 
to  retain  passively  the  position  and  condition  in 
which  they  had  been  placed,  for  we  do  not  observe 
that  they  resist  a  change  of  this  condition  by  their 
own  mutual  attraction,  as  is  the  case  with  sulphate 
of  potash. 

Now  it  is  only  such  combinations  as  sugar,  com- 
binations, therefore,  which  possess  a  very  complex 
molecule,  which  are  capable  of  undergoing  the  de- 
compositions named  fermentation  and  putrefaction. 

We  have  seen  that  metals  acquire  a  power,  which 
they  do  not  of  themselves  possess,  namely,  that  of 
decomposing  water  and  nitric  acid,  by  simple  con- 
tact with  other  metals  in  the  act  of  chemical  combi- 
nation. We  have  also  seen,  that  peroxide  of  hydro- 
gen and  the  persulphuret  of  the  same  element,  in 
the  act  of  decomposition,  cause  other  compounds  of 
a  similar  kind,  but  of  which  the  elements  are  much 
more  strongly  combined,  to  undergo  the  same  de- 
composition, although  they  exert  no  chemical  affinity 
or  attraction  for  them  or  their  constituents.  The 
cause  which  produces  these  phenomena  will  be  also 
recognised,  by  attentive  observation,  in  those  matters 
which  excite  fermentation  or  putrefaction.  All  bod- 
ies in  the  act  of  combination  or  decomposition  have 
the  property  of  inducing  those  processes ;  or,  in 
other  words,  of  causing  a  disturbance  of  the  statical 
equilibrium  in  the  attractions  of  the  elements  of 
complex  organic  molecules,  in  consequence  of  which 


OF  BODIES  WHICH  DO  NOT  CONTAIN  NITROGEN.  305 

those  elements  group  themselves  anew,  according  to 
their  special  affinities. 

The  proofs  of  the  existence  of  this  cause  of  action 
can  be  easily  produced ;  they  are  found  in  the  char- 
acters of  the  bodies  w^hich  effect  fermentation  and 
putrefaction,  and  in  the  regularity  with  which  the 
distribution  of  the  elements  takes  place  in  the  sub- 
sequent transformations.  This  regularity  depends 
exclusively  on  the  unequal  affinity  which  they  possess 
for  each  other  in  an  isolated  condition.  The  action 
of  water  on  wood,  charcoal,  and  cyanogen,  the  sim- 
plest of  the  compounds  of  nitrogen,  suffices  to  illus- 
trate the  whole  of  the  transformations  of  organic 
bodies ;  of  those  in  which  nitrogen  is  a  constituent, 
and  of  those  in  which  it  is  absent. 


CHAPTER   IV. 

ON  THE  TRANSFORMATION  OF  BODIES  WHICH  DO  NOT  CON- 
TAIN NITROGEN  AS  A  CONSTITUENT,  AND  OF  THOSE  IN 
WHICH,  IT   IS  PRESENT. 

When  oxygen  and  hydrogen  combined  in  equal 
equivalents,  as  in  steam,  are  conducted  over  char- 
coal, heated  to  the  temperature  at  which  it  possesses 
the  power  to  enter  into  combination  with  one  of 
these  elements,  a  decomposition  of  the  steam  ensues. 
An  oxide  of  carbon  (either  carbonic  oxide  or  car- 
bonic acid)  is  under  all  circumstances  formed,  while 
the  hydrogen  of  the  water  is  liberated,  or,  if  the 
temperature  be  sufficient,  unites  with  the  carbon, 
forming  carburetted  hydrogen.  Accordingly,  the 
carbon  is  shared  between  the  elements  of  the  water, 
the  oxygen  and  hydrogen.  Now  a  participation  of 
this  kind,  but  even  more  complete,  is  observed  in 
every  transformation,  whatever  be  the  nature  of  the 
causes  by  which  it  is  effected. 
26^ 


306  CHEMICAL  TRANSFORMATIONS 

Acetic  and  meconic*  acids  suffer  a  true  transform- 
ation under  the  influence  of  heat,  that  is,  their  com- 
ponent elements  are  disunited,  and  form  new  com- 
pounds without  any  of  them  being  singly  disen- 
gaged. Acetic  acid  is  converted  into  acetone  and 
carbonic  acid  (C4  H3  03=  C3  H3  0  +  C02),  and 
meconic  acid  into  carbonic  acid  and  komenic  acid ; 
whilst  by  the  influence  of  a  higher  temperature,  the 
latter  is  further  decomposed  into  pyromeconic  acid 
and  carbonic  acid. 

'  Now  in  these  cases  the  carbon  of  the  bodies  de- 
composed is  shared  between  the  oxygen  and  hydro- 
gen ;  part  of  it  unites  with  the  oxygen  and  forms 
carbonic  acid,  whilst  the  other  portion  enters  into 
combination  with  the  hydrogen,  and  an  oxide  of  a 
carbo-hydrogen  is  formed,  in  which  all  the  hydrogen 
is  contained. 

In  a  similar  manner,  when  alcohol  is  exposed  to  a 
gentle  red  heat,  its  carbon  is  shared  between  the 
elements  of  the  water,  —  an  oxide  of  a  carbo-hydro- 
gen which  contains  all  the  oxygen,  and  some  gaseous 
compounds  of  carbon  and  hydrogen  being  produced. 

It  is  evident,  that  during  transformations  caused 
by  heat,  no  foreign  affinities  can  be  in  play,  so  that 
the  new  compounds  must  result  merely  from  the 
elements  arranging  themselves,  according  to  the 
degree  of  their  mutual  affinities,  into  new  combina- 
tions, which  are  constant  and  unchangeable  in  the 
conditions  under  which  they  were  originally  formed, 
but  undergo  changes  when  these  conditions  become 
different.  If  we  compare  the  products  of  two  bod- 
ies, similar  in  composition  but  different  in  properties, 
which  are  subjected  to  transformations  by  two  differ- 
ent causes,  we  find  that  the  manner  in  which  the 
atoms  are  transposed,  is  absolutely  the  same  in 
both. 

In  the  transformation  of  wood  in  marshy  soils,  by 
what    we    call    putrefaction,    its    carbon   is    shared 

*  An  acid  existing  in  opium,  and  named  from  the  Greek  for  poppy. 


OF  BODIES  CONTAINING  NITROGEN.  307 

between  the  oxygen  and  hydrogen  of  its  own  sub- 
stance, and  of  the  water,  —  carburetted  hydrogen  is 
consequently  evolved,  as  well  as  carbonic  acid,  both 
of  which  compounds  have  an  analogous  composition 
(CH2,  C02)* 

Thus  also  in  that  transformation  of  sugar,  which 
is  called  fermentation,  its  elements  are  divided  into 
two  portions ;  the  one,  carbonic  acid,  which  contains 
§  of  the  oxygen  of  sugar ;  and  the  other,  alcohol, 
which  contains  all  its  hydrogen. 

In  the  transformation  of  acetic  acid  produced  by 
a  red  heat,  carbonic  acid,  which  contains  §  of  the 
oxygen  of  the  acetic  acid,  is  formed,  and  acetone, 
which  contains  all  its  hydrogen. 

It  is  evident  from  these  facts,  that  the  elements 
of  a  complex  compound  are  left  to  their  special 
attractions  whenever  their  equilibrium  is  disturbed, 
from  whatever  cause  this  disturbance  may  proceed. 
It  appears,  also,  that  the  subsequent  distribution  of 
the  elements,  so  as  to  form  new  combinations,  always 
takes  place  in  the  same  way,  with  this  difference 
only,  that  the  nature  of  the  products  formed  is 
dependent  upon  the  number  of  atoms  of  the  elements 
which  enter  into  action ;  or,  in  other  words,  that  the 
products  differ  ad  infinitum^  according  to  the  com- 
position of  the  original  substance. 


ON  THE  TRANSFORMATION  OF  BODIES  CONTAINING    NITROGEN. 

When  those  substances  are  examined  which  are 
most  prone  to  fermentation  and  putrefaction,  it  is 
found  that  they  are  all,  without  exception,  bodies 
which  contain  nitrogen.  In  many  of  these  com- 
pounds, a  transposition  of  their  elements  occurs 
spontaneously  as  soon  as  they  cease  to  form  a  part 
of  a  living  organism ;  that  is,  when  they  are  drawn 

*  C  carbon,  H  hydrogen,  O  oxygen. 


308  CHEMICAL  TRANSFORMATIONS 

out  of  the  sphere  of  attraction  in  which  alone  they 
are  able  to  exist. 

There  are,  indeed,  bodies  destitute  of  nitrogen, 
which  possess  a  certain  degree  of  stability  only 
when  in  combination,  but  which  are  unknown  in  an 
isolated  condition,  because  their  elements,  freed  from 
the  power  by  which  they  were  held  together,  arrange 
themselves  according  to  their  own  natural  attrac- 
tions. Hypermanganic,  manganic,  and  hyposulphu- 
rous  acids,  belong  to  this  class  of  substances,  which 
however  are  rare. 

The  case  is  very  different  with  azotized  bodies. 
It  would  appear  that  there  is  some  peculiarity  in  the 
nature  of  nitrogen,  which  gives  its  compounds  the 
power  to  decompose  spontaneously  with  so  much 
facility.  Now,  nitrogen  is  known  to  be  the  most 
indifferent  of  all  the  elements ;  it  evinces  no  partic- 
ular attraction  to  any  one  of  the  simple  bodies;  and 
this  character  it  preserves  in  all  its  combinations,  a 
character  which  explains  the  cause  of  its  easy  sep- 
aration from  the  matters  with  which  it  is  united. 

It  is  only  when  the  quantity  of  nitrogen  exceeds 
a  certain  limit,  that  azotized  compounds  have  some 
degree  of  permanence,  as  is  the  case  with  melamin, 
ammelin,  &c.  Their  liability  to  change  is  also  dimin- 
ished, when  the  quantity  of  nitrogen  is  very  small 
in  proportion  to  that  of  the  other  elements  with 
which  it  is  united,  so  that  their  mutual  attractions 
preponderate. 

This  easy  transposition  of  atoms  is  best  seen  in 
the  fulminating  silvers,  in  fulminating  mercury,  in 
the  iodide  or  chloride  of  nitrogen,  and  in  all  fulmin- 
ating compounds. 

All  other  azotized  substances  acquire  the  same 
power  of  decomposition,  when  the  elements  of  water 
are  brought  into  play;  and  indeed,  the  greater  part 
of  them  are  not  capable  of  transformation,  while 
this  necessary  condition  to  the  transposition  of  their 
atoms  is  absent.  Even  the  compounds  of  nitrogen, 
which  are  most  liable  to  change,  such  as  those  which 


OF  BODIES  CONTAINING  NITROGEN.  309 

are  found  in  animal  bodies,  do  not  enter  into  a  state 
of  putrefaction  when  dry. 

The  result  of  the  known  transformations  of  azo- 
tized  substances  proves,  that  the  water  does  not 
merely  act  as  a  medium  in  which  motion  is  permitted 
to  the  elements  in  the  act  of  transposition,  but  that 
its  influence  depends  on  chemical  affinity.  When 
the  decomposition  of  such  substances  is  effected 
with  the  assistance  of  water,  their  nitrogen  is  in- 
variably liberated  in  the  form  of  ammonia.  This  is 
a  fixed  rule  without  any  exceptions,  whatever  may  be 
the  cause  which  produces  the  decompositions.  All 
organic  compounds  containing  nitrogen,  evolve  the 
whole  of  that  element  in  the  form  of  ammonia  when 
acted  on  by  alkalies.  Acids,  and  increase  of  tempera- 
ture, produce  the  same  effect.  It  is  only  when  there  is 
a  deficiency  of  water  or  its  elements,  that  cyanogen 
or  other  azotized  compounds  are  produced. 

From  these  facts  it  may  be  concluded,  that  am- 
monia is  the  most  stable  compound  of  nitrogen ;  and 
that  hydrogen  and  nitrogen  possess  a  degree  of 
affinity  for  each  other  surpassing  the  attraction  of 
the  latter  body  for  any  other  element. 

Already,  in  considering  the  transformations  of  sub- 
stances destitute  of  nitrogen,  we  have  recognised 
the  great  affinity  of  carbon  for  oxygen  as  a  power- 
ful cause  for  effecting  the  disunion  of  the  elements 
of  a  complex  organic  atom  in  a  definite  manner.  But 
carbon  is  also  invariably  contained  in  azotized  or- 
ganic compounds,  while  the  great  affinity  of  nitrogen 
for  hydrogen  furnishes  a  new  and  powerful  cause, 
facilitating  the  transposition  of  their  component 
parts.  Thus,  in  the  bodies  which  do  not  contain 
nitrogen  we  have  one  element,  and  in  those  in  which 
that  substance  is  present,  two  elements,  which  mutu- 
ally share  the  elements  of  water.  Hence  there  are 
two  opposite  affinities  at  play,  which  mutually 
strengthen  each  other's  action. 

Now  we  know,  that  the  most  pow^erful  attractions 
may  be  overcome  by  the  influence  of  two  affinities. 


310  CHEMICAL  TRANSFORMATIONS 

Thus,  a  decomposition  of  alumina  may  be  effected 
with  the  greatest  facility,  when  the  affinity  of  char- 
coal for  oxygen,  and  of  chlorine  for  aluminium,  are 
both  put  in  action,  although  neither  of  these  alone 
has  any  influence  upon  it.  There  is  in  the  nature 
and  constitution  of  the  compounds  of  nitrogen  a  kind 
of  tension  of  their  component  parts,  and  a  strong 
disposition  to  yield  to  transformations,  which  effect 
spontaneously  the  transposition  of  their  atoms  on  the 
instant  that  water  or  its  elements  are  brought  in 
contact  with  them. 

The  characters  of  the  hydrated  cyanic  acid,  one 
of  the  simplest  of  all  the  compounds  of  nitrogen,  are 
perhaps  the  best  adapted  to  convey  a  distinct  idea 
of  the  manner  in  which  the  atoms  are  disposed  of  in 
transformations.  This  acid  contains  nitrogen,  hy- 
drogen, and  oxygen,  in  such  proportions,  that  the 
addition  of  a  certain  quantity  of  the  elements  of 
water  is  exactly  sufficient  to  cause  the  oxygen  con- 
tained in  the  water  and  acid  to  unite  with  the  car- 
bon and  form  carbonic  acid,  and  the  hydrogen  of  the 
water  to  combine  with  the  nitrogen  and  form  am- 
monia. The  most  favorable  conditions  for  a  com- 
plete transformation  are,  therefore,  associated  in 
these  bodies,  and  it  is  well  known,  that  the  disunion 
takes  place  on  the  instant  in  which  the  cyanic  acid 
and  water  are  brought  into  contact,  the  mixture  being 
converted  into  carbonic  acid  and  ammonia,  with  brisk 
effervescence. 

This  decomposition  may  be  considered  as  the  type 
of  the  transformations  of  all  azotized  compounds;  it 
is  putrefaction  in  its  simplest  and  most  perfect  form, 
because  the  new  products,  the  carbonic  acid  and 
ammonia,  are  incapable  of  further  transformations. 

Putrefaction  assumes  a  totally  different  and  much 
more  complicated  form,  when  the  products,  which  are 
first  formed,  undergo  a  further  change.  In  these 
cases  the  process  consists  of  several  stages,  of  which 
it  is  impossible  to  determine  when  one  ceases  and 
the  other  begins. 


OF  BODIES  CONTAINING  NITROGEN.  311 

The  transformations  of  cyanogen,  a  body  com- 
posed of  carbon  and  nitrogen,  and  the  simplest  of  all 
the  compounds  of  nitrogen,  will  convey  a  clear  idea 
of  the  great  variety  of  products  which  are  produced 
in  such  a  case:  it  is  the  only  example  of  the  putre- 
faction of  an  azotized  body  which  has  been  at  all 
accurately  studied. 

A  solution  of  cyanogen  in  water  becomes  turbid 
after  a  short  time,  and  deposits  a  black,  or  brownish 
black  matter,  which  is  a  combination  of  ammonia 
with  another  body,  produced  by  the  simple  union  of 
cyanogen  with  water.  This  substance  is  insoluble 
in  water,  and  is  thus  enabled  to  resist  further  change. 

A  second  transformation  is  effected  by  the  cyano- 
gen being  shared  between  the  elements  of  the  water, 
in  consequence  of  which  cyanic  acid  is  formed  by  a 
certain  quantity  of  the  cyanogen  combining  w^th  the 
oxygen  of  the  water,  while  hydrocyanic  acid  is  also 
formed  by  another  portion  of  the  cyanogen  uniting 
with  the  hydrogen  which  was  liberated. 

Cyanogen  experiences  a  third  transformation,  by 
which  a  complete  disunion  of  its  elements  takes 
place,  these  being  divided  between  the  constituents 
of  the  water.  Oxalic  acid  is  the  one  product  of  this 
disunion,  and  ammonia  the  other. 

Cyanic  acid,  the  formation  of  which  has  been 
mentioned  above,  cannot  exist  in  contact  with  water, 
being  decomposed  immediately  into  carbonic  acid 
and  ammonia.  The  cyanic  acid,  however,  newly 
formed  in  the  decomposition  of  cyanogen,  escapes 
this  decomposition  by  entering  into  combination  w^ith 
the  free  ammonia,  by  which  urea  *  is  produced. 

The  hydrocyanic  acid  is  also  decomposed  into  a 
brown  matter  which  contains  hydrogen  and  cyano- 
gen, the  latter  in  greater  proportion  than  it  does  in 
the  gaseous  state.  Oxalic  acid,  urea,  and  carbonic 
acid,  are  also  formed  by  its  decomposition,  and /orm- 

*  See  page  87,  note. 


312  CHEMICAL  TRANSFORMATIONS. 

ic  acid  and  ammonia  are  produced  by  the  decompo- 
sition of  its  radical. 

Thus,  a  substance  into  the  composition  of  which 
only  two  elements  (carbon  and  nitrogen)  enter,  yields 
eight  totally  different  products.  Several  of  these 
products  are  formed  by  the  transformation  of  the 
original  body,  its  elements  being  shared  between  the 
constituents  of  water ;  others  are  produced  in  con- 
sequence of  a  further  disunion  of  those  first  formed. 
The  urea  and  carbonate  of  ammonia  are  generated 
by  the  combination  of  two  of  the  products,  and  in 
their  formation  the  whole  of  the  elements  have  as- 
sisted. 

These  examples  show,  that  the  results  of  decompo- 
sition by  fermentation  or  putrefaction  comprehend 
very  different  phenomena.  The  first  kind  of  trans- 
formation is,  the  transposition  of  the  elements  of  one 
complex  compound,  by  which  new  compounds  are 
produced  with  or  without  the  assistance  of  the  ele- 
ments of  water.  In  the  products  newly  formed  in 
this  manner,  either  the  same  proportions  of  those 
component  parts  which  were  contained  in  the  mat- 
ter before  transformation,  are  found,  or  with  them, 
an  excess,  consisting  of  the  constituents  of  water, 
which  had  assisted  in  promoting  the  disunion  of  the 
elements. 

The  second  kind  of  transformation  consists  of 
the  transpositions  of  the  atoms  of  two  or  more  com- 
plex compounds,  by  which  the  elements  of  both 
arrange  themselves  mutually  into  new  products,  with 
or  without  the  cooperation  of  the  elements  of  water. 
In  this  kind  of  transformation,  the  new  products 
contain  the  sum  of  the  constituents  of  all  the  com- 
pounds which  had  taken  a  part  in  the  decomposition. 

The  first  of  these  two  modes  of  decomposition  is 
that  designated  fermentation^  the  second  putrefac- 
tion ;  and  when  these  terms  are  used  in  the  following 
pages,  it  will  always  be  to  distinguish  the  two  pro- 
cesses above  described,  which  are  so  different  in 
their  results. 


FERMENTATION  OF  SUGAR.  313 


CHAPTER  V. 

FERMENTATION  OF  SUGAR. 

The  peculiar  decomposition,  which  sugar  suffers, 
may  be  viewed  as  a  type  of  all  tKe  transformations 
designated  fermentation.'* 

Thenard  obtained  from  100  grammes  f  of  cane- 
sugar  0-5262  of  absolute  alcohol.  100  parts  of  sugar 
from  the  cane  yield,  therefore,  103-89  parts  of  car- 
bonic acid  and  alcohol.  'The  entire  carbon  in  these 
products  is  equal  to  42  parts,  which  is  exactly  the 
quantity  originally  contained  in  the  sugar. 

The  analysis  of  sugar  from  the  cane,  proves  that 
it  contains  the  elements  of  carbonic  acid  and  alco- 
hol, minus  1  atom  of  water.  The  alcohol  and  car- 
bonic acid  produced  by  the  fermentation  of  a  certain 
quantity  of  sugar,  contained  together  one  equivalent 
of  oxygen,  and  one  equivalent  of  hydrogen,  the  ele- 
ments, therefore,  of  one  equivalent  of  water,  more 
than  the  sugar  contained.  The  excess  of  weight  in 
the  products  is  thus  explained  most  satisfactorily ; 
it  is  owing,  namely,  to  the  elements  of  water  having 
taken  part  in  the  metamorphosis  of  the  sugar. 

It  is  known,  that  1  atom  of  sugar  contains  12 
equivalents  of  carbon,  both  from  the  proportions  in 
which  it  unites  with  bases,  and  from  the  composition 

*  When  yeast  is  made  into  a  thin  paste  with  water,  and  1  cubic  centi- 
metre of  this  mixture  introduced  into  a  graduated  glass  receiver  filled 
with  mercury,  in  which  are  already  19  grammes  of  a  solution  of  cane- 
sugar,  containing  I  gramme  of  pure  solid  sugar;  it  is  found,  after  the 
mixture  has  been  exposed  for  24  hours  to  a  temperature  of  from  20  to 
25  C.  (68-77  F.),  that  a  volume  of  carbonic  acid  has  been  formed, 
which,  at  0°  C.  (32°  F.)  and  an  atmospheric  pressure  indicated  by  076 
metre  Bar.  would  be  from  245  to  250  cubic  centimetres.  But  to  this 
quantity  we  must  add  11  cubic  centimetres  of  carbonic  acid,  with 
which  the  11  grammes  of  liquid  would  be  saturated,  so  that  in  all  255 
-259  cubic  centimetres  of  carbonic  acid  are  obtained.  This  volume 
of  carbonic  acid  corresponds  to  from  0503  to  0*5127  grammes  by 
weight.  —  L. 

t  The  gramme  equals  15-4440  grains. 

27 


314  FERMENTATION  OF  SUGAR. 

of  saccharic  acid,  the  product  of  its  oxidation.  Now 
none  of  these  atoms  of  carbon  are  contained  in  the 
sugar  as  carbonic  acid,  because  the  whole  quantity  is 
obtained  as  oxalic  acid,  when  sugar  is  treated  with 
hypermanganate  of  potash  (Gregory);  and  as  oxalic 
acid  is  a  lower  degree  of  the  oxidation  of  carbon 
than  carbonic  acid,  it  is  impossible  to  conceive  that 
the  lower  degree  should  be  produced  from  the  high- 
er, by  means  of  one  of  the  most  powerful  agents  of 
oxidation  which  we  possess. 

It  can  be  also  proved,  that  the  hydrogen  of  the 
sugar  does  not  exist  in  it  in  the  form  of  alcohol,  for 
it  IS  converted  into  water  and  a  kind  of  carbona- 
ceous matter,  when  treated  with  acids,  particularly 
with  such  as  contain  no  oxygen ;  and  this  manner 
of  decomposition  is  never  suffered  by  a  compound 
of  alcohol. 

Sugar  contains,  therefore,  neither  alcohol  nor  car- 
bonic acid,  so  that  these  bodies  must  be  produced  by 
a  different  arrangement  of  its  atoms,  and  by  their 
union  with  the  elements  of  water. 

In  this  metamorphosis  of  sugar,  the  elements  of 
the  yeast,  by  contact  with  which  its  fermentation 
was  effected,  take  no  appreciable  part  in  the  trans- 
position of  the  elements  of  the  sugar;  for  in  the 
products  resulting  from  the  action,  we  find  no  com- 
ponent part  of  this  substance. 

We  may  now  study  the  fermentation  of  a  vegeta- 
ble juice,  which  contains  not  only  saccharine  matter, 
but  also  such  substances  as  albumen  and  gluten. 
The  juices  of  parsnips,  beet-roots,  and  onions,  are 
well  adapted  for  this  purpose.  When  such  a  juice 
is  mixed  with  yeast  at  common  temperatures,  it  fer- 
ments like  a  solution  of  sugar.  Carbonic  acid  gas 
escapes  from  it  with  effervescence,  and  in  the  liquid, 
alcohol  is  found  in  quantity  exactly  corresponding  to 
that  of  the  sugar  originally  contained  in  the  juice. 
But  such  a  juice  undergoes  spontaneous  decomposi- 
tion at  a  temperature  of  from  95^  to  104°  (350  — 40^ 
C).  Gases  possessing  an  offensive  smell  are  evolved 


YEAST  OR  FERMENT.  315 

in  considerable  quantity,  and  when  the  liquor  is  ex- 
amined after  the  decomposition  is  completed,  no  al- 
cohol can  be  detected.  The  sugar  has  also  disap- 
peared, and  with  it  all  the  azotized  compounds  which 
existed  in  the  juice  previously  to  its  fermentation. 
Both  were  decomposed  at  the  same  time ;  the  nitro- 
gen of  the  azotized  compounds  remains  in  the  liquid 
as  ammonia,  and,  in  addition  to  it,  there  are  three 
new  products,  formed  from  the  component  parts  of 
the  juice.  One  of  these  is  lactic  acid,  the  slightly 
volatile  compound  found  in  the  animal  organism ; 
the  other  is  the  crystalline  body,  which  forms  the 
principal  constituent  of  manna;  and  the  third  is  a 
mass  resembling  gum-arabic,  which  forms  a  thick 
viscous  solution  with  water.  These  three  products 
weigh  more  than  the  sugar  contained  in  the  juice, 
even  without  calculating  the  weight  of  the  gaseous 
products.  Hence,  they  are  not  produced  from  the 
elements  of  the  sugar  alone.  None  of  these  three 
substances  could  be  detected  in  the  juice  before  fer- 
mentation. They  must,  therefore,  have  been  formed 
by  the  interchange  of  the  elements  of  the  sugar  with 
those  of  the  foreign  substances  also  present.  It  is 
this  mixed  transformation  of  two  or  more  compounds 
which  receives  the  special  name  of  putrefaction. 


YEAST    OR    FERMENT. 

When  attention  is  directed  to  the  condition  of 
those  substances,  which  possess  the  power  of  induc- 
ing fermentation  and  putrefaction  in  other  bodies, 
evidences  are  found  in  their  general  characters,  and 
in  the  manner  in  which  they  combine,  that  they  all 
are  bodies,  the  atoms  of  which  are  in  the  act  of 
transposition. 

The  characters  of  the  remarkable  matter,  which  is 
deposited  in  an  insoluble  state  during  the  fermenta- 
tion of  beer,  wine,  and  vegetable  juices,  may  first  be 
studied. 


316  .  YEAST  OR  FERMENT. 

This  substance,  which  has  been  called  yeast  ov  fer- 
ment, from  the  power  which  it  possesses  of  causing 
fermentation  in  sugar,  or  saccharine  vegetable  juices, 
possesses  all  the  characters  of  a  compound  of  nitro- 
gen in  the  state  of  ^putrefaction  and  eremacausis. 

Like  wood  in  the  state  of  eremacausis,  yeast  con- 
verts the  oxygeji  of  the  surrounding  air  into  carbon- 
ic acid,  but  it  also  evolves  this  gas  from  its  own 
mass,  like  bodies  in  the  state  of  putrefaction.  (Colin.) 
When  kept  under  water,  it  emits  carbonic  acid,  ac- 
companied by  gases  of  an  offensive  smell,  (Thenard,) 
and  is  at  last  converted  into  a  substance  resembling 
old  cheese.  (Proust.)  But  when  its  own  putrefaction 
is  completed,  it  has  no  longer  the  power  of  inducing 
fermentation  in  other  bodies.  The  presence  of  wa- 
ter is  quite  necessary  for  sustaining  the  properties 
of  ferment,  for  by  simple  pressure  its  power  to  ex- 
cite fermentation  is  much  diminished,  and  is  com- 
pletely destroyed  by  drying.  Its  action  is  arrested 
also  by  the  temperature  of  boiling  water,  by  alcohol, 
common  salt,  an  excess  of  sugar,  oxide  of  mercury, 
corrosive  sublimate,  pyroligneous  acid,  sulphurous 
acid,  nitrate  of  silver,  volatile  oils,  and  in  short  by 
all  antiseptic  substances. 

The  insoluble  part  of  the  substance  called  ferment 
does  not  cause  fermentation.  For  when  the  yeast 
from  wine  or  beer  is  carefully  washed  with  water, 
care  being  taken  that  it  is  always  covered  with  this 
fluid,  the  residue  does  not  produce  fermentation. 

The  soluble  part  of  ferment  likewise  does  not  excite 
fermentation.  An  aqueous  infusion  of  yeast  may  be 
mixed  with  a  solution  of  sugar,  and  preserved  in 
vessels  from  which  the  air  is  excluded,  w^ithout  eith- 
er experiencing  the  slightest  change.  What  then, 
we  may  ask,  is  the  matter  in  ferment  which  excites 
fermentation,  if  neither  the  soluble  nor  insoluble 
parts  possess  the  power  ?  This  question  has  been 
answered  by  Colin  in  the  most  satisfactory  manner. 
He  has  shown,  that  in  reality  it  is  the  soluble  part. 
But  before  it  obtains  this  power,  the  decanted  infu- 


ITS  PROPERTIES.  317 

sion  must  be  allowed  to  cool  in  contact  with  the  air, 
and  to  remain  some  time  exposed  to  its  action.  When 
introduced  into  a  solution  of  sugar  in  this  state,  it 
produces  a  brisk  fermentation ;  but  without  previous 
exposure  to  the  air,  it  manifests  no  such  property. 

The  infusion  absorbs  oxygen  during  its  exposure 
to  the  air,  and  carbonic  acid  may  be  found  in  it  after 
a  short  time. 

Yeast  produces  fermentation  in  consequence  of  the 
progressive  decomposition,  which  it  suffers  from  the 
action  of  air  and  water. 

Now  when  yeast  is  made  to  act  on  sugar,  it  is 
found,  that  after  the  transformation  of  the  latter 
substance  into  carbonic  acid  and  alcohol  is  com- 
pleted, part  of  the  yeast  itself  has  disappeared. 

From  20  parts  of  fresh  yeast  from  beer,  and  100 
parts  of  sugar,  Thmard  obtained,  after  the  fermen- 
tation was  completed,  13*7  parts  of  an  insoluble 
residue,  which  diminished  to  10  parts  when  employed 
in  the  same  way  with  a  fresh  portion  of  sugar. 
These  ten  parts  were  white,  possessed  of  the  prop- 
erties of  woody  fibre,  and  had  no  further  action  on 
sugar. 

It  is  evident,  therefore,  that  during  the  fermenta- 
tion of  sugar  by  yeast,  both  of  these  substances 
suffer  decomposition  at  the  same  time,  and  disappear 
in  consequence.  But  if  yeast  be  a  body  which  ex- 
cites fermentation  by  being  itself  in  a  state  of  de- 
composition, all  other  matters  in  the  same  condition 
should  have  a  similar  action  upon  sugar ;  and  this  is 
in  reality  the  case.  Muscle,  urine,  isinglass,  osma- 
zome,*  albumen,  cheese,  gliadine,  gluten,  legumin, 
and  blood,  when  in  a  state  of  putrefaction,  have  all 
the  power  of  producing  the  putrefaction,  or  fermen- 
tation of  a  solution  of  sugar.  Yeast,  w^hich  by  con- 
tinued washing  has  entirely  lost  the  property  of  in- 
ducing fermentation,  regains  it  when  its  putrefaction 

*  An  extractive  animal  matter  on  which  the  peculiar  flavor  of  broth 
is  supposed  to  depend ;  hence  its  name,  from  the  Greek  for  odor  and 
broth. 

27* 


318  YEAST  OF  FERMENT. 

has  recommenced,  in  consequence  of  its  being  kept  in 
a  warm  situation  for  some  time. 

Yeast  and  putrefying  animal  and  vegetable  mat- 
ters act  as  peroxide  of  hydrogen  does  on  oxide  of 
silver,  when  they  induce  bodies  with  which  they  are 
in  contact  to  enter  into  the  same  state  of  decompo- 
sition. The  disturbance  in  the  attraction  of  the  con- 
stituents of  the  peroxide  of  hydrogen  effects  a  dis- 
turbance in  the  attraction  of  the  elements  of  the 
oxide  of  silver,  the  one  being  decomposed,  on  ac- 
count of  the  decomposition  of  the  other. 

Now  if  we  consider  the  process  of  the  fermentation 
of  pure  sugar,  in  a  practical  point  of  view,  we  meet 
with  two  facts  of  constant  occurrence.  When  the 
quantity  of  ferment  is  too  small  in  proportion  to  that 
of  the  sugar,  its  putrefaction  will  be  completed  before 
the  transformation  of  all  the  sugar  is  effected.  Some 
sugar  here  remains  undecomposed,  because  the  cause 
of  its  transformation  is  absent,  viz.  contact  with  a 
body  in  a  state  of  decomposition. 

But  when  the  quantity  of  ferment  predominates,  a 
certain  quantity  of  it  remains  after  all  the  sugar  has 
fermented,  its  decomposition  proceeding  very  slowly, 
on  account  of  its  insolubility  in  water.  This  residue 
of  ferment  is  still  able  to  induce  fermentation,  when 
introduced  into  a  fresh  solution  of  sugar,  and  retains 
the  same  power  until  it  has  passed  through  all  the 
stages  of  its  own  transformation.  Hence,  a  certain 
quantity  of  yeast  is  necessary  in  order  to  effect  the 
transformation  of  a  certain  portion  of  sugar,  not 
because  it  acts  by  its  quantity  in  increasing  any 
affinity,  but  because  its  influence  depends  solely  on 
its  presence,  and  its  presence  is  necessary,  until  the 
last  atom  of  sugar  is  decomposed. 

These  facts  and  observations  point  out  the  ex- 
istence of  a  new  cause,  which  effects  combinations 
and  decompositions.  This  cause  is  the  action  which 
bodies  in  a  state  of  combination  or  decomposition 
exercise  upon  substances,  the  component  parts  of 
which  are  united  together  by  a  feeble  affinity.     This 


AZOTIZED  MATTERS  THE  CAUSE  OF  PUTREFACTION.        319 

action  resembles  a  peculiar  power,  attached  to  a 
body  in  the  state  of  combination  or  decomposition, 
but  exerting  its  influence  beyond  the  sphere  of  its 
own  attractions.  We  are  now  able  to  account  satis- 
factorily for  many  known  phenomena. 

A  large  quantity  of  hippuric  acid  may  be  obtained 
from  the  fresh  urine  of  a  horse,  by  the  addition  of 
muriatic  acid;  but  when  the  urine  has  undergone 
putrefaction,  no  trace  of  it  can  be  discovered.  The 
urine  of  man  contains  a  considerable  quantity  of 
urea;  but  when  the  urine  putrefies,  the  urea  entirely 
disappears.  When  urea  is  added  to  a  solution  of 
sugar  in  the  state  of  fermentation,  it  is  decomposed 
into  carbonic  acid  and  ammonia.  No  asparagin* 
can  be  detected  in  a  putrefied  infusion  of  asparagin, 
liquorice-root,  or  the  root  of  marshmallow  (^Althcea 
officinalis). 

It  has  already  been  mentioned,  that  the  strong 
affinity  of  nitrogen  for  hydrogen,  and  that  of  carbon 
for  oxygen,  are  the  cause  of  the  facility  with  which 
the  elements  of  azotized  compounds  are  disunited ; 
those  affinities  aiding  each  other,  inasmuch  as  by 
virtue  of  them  different  elements  of  the  compounds 
strive  to  take  possession  of  the  different  elements 
of  water.  Now  since  it  is  found  that  no  body  desti- 
tute of  nitrogen,  possesses,  when  pure,  the  property 
of  decomposing  spontaneously  whilst  in  contact  with 
water,  we  must  ascribe  this  property  which  azotized 
bodies  possess  in  so  eminent  a  degree,  to  something 
peculiar  in  the  nature  of  the  compounds  of  nitrogen, 
and  to  their  constituting,  in  a  certain  measure,  more 
highly  organized  atoms. 

Every  azotized  constituent  of  the  animal  or  vege- 
table organism  runs  spontaneously  into  putrefaction, 
when  exposed  to  moisture  and  a  high  temperature. 

Azotized  matters  are,  accordingly,  the  only  causes 
of  fermentation  and  putrefaction  in  vegetable  sub- 
stances. 

*   A  peculiar  principle   obtained  from  asparagus.     See  Brande's 
Chemistry f  p.  1042. 


320  YEAST  OR  FERMENT. 

Putrefaction,  on  account  of  its  effects,  as  a  mixed 
transformation  of  many  different  substances,  may  be 
classed  with  the  most  powerful  processes  of  deoxi- 
dation,  by  which  the  strongest  affinities  are  over- 
come. 

When  a  solution  of  gypsum  in  water  is  mixed  with 
a  decoction  of  sawdust,  or  any  other  organic  matter 
capable  of  putrefaction,  and  preserved  in  well-closed 
vessels,  it  is  found  after  some  time,  that  the  solution 
contains  no  more  sulphuric  acid,  but  in  its  place  car- 
bonic and  free  hydrosulphuric  acid,  between  which 
the  lime  of  the  gypsum  is  shared.  In  stagnant  water 
containing  sulphates  in  solution,  cry&tallized  pyrites 
is  observed  to  form  on  the  decaying  roots. 

Now  we  know,  that  in  the  putrefaction  of  wood 
under  water,  when  air  therefore  is  excluded,  a  part 
of  its  carbon  combines  with  the  oxygen  of  the  water, 
as  well  as  with  the  oxygen  which  the  wood  itself 
contains ;  whilst  its  hydrogen  and  that  of  the  de- 
composed water  are  liberated  either  in  a  pure  state, 
or  as  carburetted  hydrogen.  The  products  of  this 
decomposition  are  of  the  same  kind  as  those  genera- 
ted when  steam  is  conducted  over  red-hot  charcoal. 

It  is  evident,  that  if  with  the  water  a  substance 
containing  a  large  quantity  of  oxygen,  such  as  sul- 
phuric acid,  be  also  present,  the  matters  in  the  state 
of  putrefaction  will  make  use  of  the  oxygen  of  that 
substance  as  well  as  that  of  the  water,  in  order  to 
form  carbonic  acid ;  and  the  sulphur  and  hydrogen 
being  set  free  will  combine  whilst  in  the  nascent 
state,  producing  hydrosulphuric  acid,  which  will  be 
again  decomposed  if  metallic  oxides  be  present ;  and 
the  results  of  this  second  decomposition  will  be  water 
and  metallic  sulphurets. 

The  putrefied  leaves  of  woad  (^Isatis  tinctoria),  in 
contact  with  indigo-blue,  water,  and  alkalies,  suffer 
further  decomposition,  and  the  indigo  is  deoxidized 
and  dissolved. 

The  mannite  formed  by  the  putrefaction  of  beet- 
roots and  other  plants  which  contain  sugar,  contains 


DIFFERENCE  OF  FERMENTATION  AND  PUTREFACTION.      321 

the  same  number  of  equivalents  of  carbon  and  hydro- 
gen as  the  sugar  of  grapes,  but  two  atoms  less  of 
oxygen ;  and  it  is  highly  probable  that  it  is  produced 
from  sugar  of  grapes,  contained  in  those  plants,  in 
precisely  the  same  manner  as  indigo-blue  is  con- 
verted into  deoxidized  white  indigo. 

During  the  putrefaction  of  gluten,  carbonic  acid 
and  pure  hydrogen  gas  are  evolved ;  phosphate, 
acetate,  caseate,  and  lactate  of  ammonia  being  at 
the  same  time  produced  in  such  quantity,  that  the 
further  decomposition  of  the  gluten  ceases.  But 
when  the  supply  of  water  is  renewed,  the  decompo- 
sition begins  again,  and  in  addition  to  the  salts  just 
mentioned,  carbonate  of  ammonia  and  a  white  crys- 
talline matter  resembling  mica  (caseous  oxide)  are 
formed,  together  with  hydrosulphate  of  ammonia, 
and  a  mucilaginous  substance  coagulable  by  chlorine. 
Lactic  acid  is  almost  always  produced  by  the  putre- 
faction of  organic  bodies. 

We  may  now  compare  fermentation  and  putrefac- 
tion with  the  decomposition  which  organic  com- 
pounds suffer  under  the  influence  of  a  high  tempera- 
ture. Dry  distillation  would  appear  to  be  a  process 
of  combustion  or  oxidation  going  on  in  the  interior 
of  a  substance,  in  which  a  part  of  the  carbon  unites 
with  all  or  part  of  the  oxygen  of  the  compound, 
while  other  new  compounds  containing  a  large  pro- 
portion of  hydrogen  are  necessarily  produced.  Fer- 
mentation may  be  considered  as  a  process  of  com- 
bustion or  oxidation  of  a  similar  kind,  taking  place 
in  a  liquid  between  the  elements  of  the  same  mattery 
at  a  very  slightly  elevated  temperature ;  and  putre- 
faction as  a  process  of  oxidation,  in  which  the  oxy- 
gen of  all  the  substances  present  comes  into  play. 


322  EREMACAUSIS  OR  DECAY. 


CHAPTER  VI. 

EREMACAUSIS,  OR  DECAY. 

In  organic  nature,  besides  the  processes  of  decom- 
position named  fermentation  and  putrefaction,  an- 
other and  not  less  striking  class  of  changes  occurs, 
which  bodies  suffer  from  the  influence  of  the  air. 
This  is  the  act  of  gradual  combination  of  the  com- 
bustible elements  of  a  body  with  the  oxygen  of  the 
air ;  a  slow  combustion  or  oxidation,  to  which  we 
shall  apply  the  term  of  eremacmisis. 

The  conversion  of  wood  into  humus,  the  formation 
of  acetic  acid  out  of  alcohol,  nitrification,  and  numer- 
ous other  processes,  are  of  this  nature.  Vegetable 
juices  of  every  kind,  parts  of  animal  and  vegetable 
substances,  moist  sawdust,  blood,  &c.,  cannot  be 
exposed  to  the  air,  without  suffering  immediately  a 
progressive  change  of  color  and  properties,  during 
which  oxygen  is  absorbed.  These  changes  do  not 
take  place  when  water  is  excluded,  or  when  the 
substances  are  exposed  to  the  temperature  of  32^, 
and  it  has  been  observed  that  different  bodies  require 
different  degrees  of  heat,  in  order  to  effect  the 
absorption  of  oxygen,  and,  consequently,  their  ere- 
macausis.  The  property  of  suffering  this  change  is 
possessed  in  the  highest  degree  by  substances  con- 
taining nitrogen. 

When  vegetable  juices  are  evaporated  by  a  gentle 
heat  in  the  air,  a  brown  or  brownish-black  substance 
is  precipitated  as  a  product  of  the  action  of  oxygen 
upon  them.  This  substance,  which  appears  to  pos- 
sess similar  properties  from  whatever  juice  it  is 
obtained,  has  received  the  name  of  extractive  matter; 
it  is  insoluble  or  very  sparingly  soluble  in  water,  but 
is  dissolved  with  facility  by  alkalies.  By  the  action 
of  air  on  solid  animal  or  vegetable  matters,  a  similar 


EREMACAUSIS  OR  DECAY.  323 

:)ulverulent  brown  substance  is  formed,  and  is  known 
jj  the  name  of  humus. 

The  conditions  which  determine  the  commence- 
ment of  eremacausis  are  of  various  kinds.  Many- 
organic  substances,  particularly  such  as  are  mixtures 
3f  several  more  simple  matters,  oxidize  in  the  air 
when  simply  moistened  with  water;  others  not  until 
;they  are  subjected  to  the  action  of  alkalies;  but  the 
greatest  part  of  them  undergo  this  state  of  slow 
combustion  or  oxidation,  when  brought  in  contact 
with  other  decaying  matters. 

The  eremacausis  of  an  organic  matter  is  retarded 
or  completely  arrested  by  all  those  substances  which 
prevent  fermentation  or  putrefaction.  Mineral  acids, 
salts  of  mercury,  aromatic  substances,  empyreumatic 
oils,  and  oil  of  turpentine,  possess  a  similar  action 
in  this  respect.  The  latter  substances  have  the 
same  effect  on  decaying  bodies  as  on  phosphuretted 
hydrogen,  the  spontaneous  inflammability  of  which 
they  destroy. 

Many  bodies  which  do  not  decay  when  moistened 
with  water,  enter  into  eremacausis  when  in  contact 
with  an  alkali.  Gallic  acid,  hsematin,*  and  many 
other  compounds,  may  be  dissolved  in  water  and  yet 
remain  unaltered ;  but  if  the  smallest  quantity  of  a 
free  alkali  is  present,  they  acquire  the  property  of 
attracting  oxygen,  and  are  converted  into  a  brown 
substance  like  humus,  evolving  very  frequently  at 
the  same  time  carbonic  acid.     (Chevreul.) 

A  very  remarkable  kind  of  eremacausis  takes 
place  in  many  vegetable  substances,  when  they  are 
exposed  to  the  influence  of  air,  water,  and  ammonia. 
They  absorb  oxygen  very  rapidly,  and  form  splendid 
violet  or  red-colored  liquids,  as  in  the  case  of  orcin 
and  erythrin.  They  now  contain  an  azotized  sub- 
stance, not  in  the  form  of  ammonia. 

All  these  facts  show,  that  the  action  of  oxygen 
seldom  affects  the  carbon  of  decaying   substances, 

*  The  coloring  matter  of  logwood. 


324  EREMACAUSIS  OR  DECAY, 

and  this  corresponds  exactly  to  what  happens  in 
combustion  at  high  temperatures.  It  is  well  known, 
for  example,  that  when  no  more  oxygen  is  admitted 
to  a  compound  of  carbon  and  hydrogen  than  is  suffi- 
cient to  combine  with  its  hydrogen,  the  carbon  is  not 
burned,  but  is  separated  as  lampblack;*  while,  if 
the  quantity  of  oxygen  is  not  sufficient  even  to  con- 
sume all  the  hydrogen,  new  compounds*  are  formed, 
such  as  napthalinf  and  similar  matters,  which  con- 
tain a  smaller  proportion  of  hydrogen  than  those 
compounds  of  carbon  and  hydrogen  which  previously 
existed  in  the  combustible  substance. 

There  is  no  example  of  carbon  combining  directly 
with  oxygen  at  common  temperatures,  but  numerous 
facts  show  that  hydrogen,  in  certain  states  of  con- 
densation, possesses  that  property.  Lampblack  which 
has  been  heated  to  redness  may  be  kept  in  contact 
with  oxygen  gas,  without  forming  carbonic  acid; 
but  lampblack,  impregnated  with  oils  which  contain 
a  large  proportion  of  hydrogen,  gradually  becomes 
warm,  and  inflames  spontaneously.  The  spontaneous 
inflammability  of  the  charcoal  used  in  the  fabrication 
of  gunpowder  has  been  correctly  ascribed  to  the 
hydrogen,  which  it  contains  in  considerable  quantity; 
for  during  its  reduction  to  powder,  no  trace  of 
carbonic  acid  can  be  detected  in  the  air  surrounding 
it ;  it  is  not  formed  until  the  temperature  of  the  mass 
has  reached  a  red  heat.  The  heat  which  produces 
the  inflammation  is,  therefore,  not  caused  by  the 
oxidation  of  the  carbon. 

The  substances  which  undergo  eremacausis  may 
be  divided  into  two  classes.  The  first  class  compre- 
hends those  substances  which  unite  with  the  oxygen 
of  the  air,  without  evolving  carbonic  acid ;  and  the 
second,  such  as  emit  carbonic  acid  by  absorbing 
oxygen. 

When  the  oil  of  bitter  almonds  is  exposed  to  the 

*  As  in  the  combustion  of  spirits  of  turpentine,  now  much  employed, 
under  various  names,  in  lamps. 

t  A  substance  obtained  from  coal  tar. 


EXAMPLES  OF.  325 

iair,  it  absorbs  two  equivalents  of  oxygen,  and  is  con- 
verted into  benzoic  acid;  but  half  of  the  oxygen  ab- 
sorbed combines  with  the  hydrogen  of  the  oil,  and 
forms  water,  which  remains  in  union  with  the  anhy- 
drous benzoic  acid.* 

But,  although  it  appears  very  probable  that  the 
oxygen  acts  primarily  and  principally  upon  hydro- 
gen, the  most  combustible  constituent  of  organic 
matter  in  the  state  of  decay ;  still  it  cannot  thence 
be  concluded,  that  the  carbon  is  quite  devoid  of  the 
power  to  unite  with  oxygen,  when  every  particle  of 
it  is  surrounded  with  hydrogen,  an  element  with 
which  the  oxygen  combines  with  greater  facility. 

We  know,  on  the  contrary,  that  although  nitrogen 
cannot  be  made  to  combine  with  oxygen  directly,  yet 
it  is  oxidized  and  forms  nitric  acid,  when  mixed 
with  a  large  quantity  of  hydrogen,  and  burned  in 
oxygen  gas.  In  this  case  its  affinity  is  evidently 
increased  by  the  combustion  of  the  hydrogen,  which 
is  in  fact  communicated  to  it.  It  is  conceivable, 
that  in  a  similar  manner,  the  carbon  may  be  directly 
oxidized  in  several  cases,  obtaining  from  its  con- 
tact with  hydrogen  in  eremacausis  a  property  which 
it  does  not  itself  possess  at  common  temperatures. 
But  the  formation  of  carbonic  acid  during  the  ere- 
macausis of  bodies  containing  hydrogen,  must  in 
most  cases  be  ascribed  to  another  cause.     It  appears 

*  According  to  the  experiments  of  Dobereiner,  100  parts  of  pyrogal- 
lic  acid  absorb  38*09  parts  of  oxygen  when  in  contact  with  ammonia 
and  water ;  the  acid  being  changed  in  consequence  of  this  absorption 
into  a  mouldy  substance,  which  contains  less  oxygen  than  the  acid  it- 
self. It  is  evident,  that  the  substance  which  is  formed  is  not  a  higher 
oxide ;  and  it  is  found,  on  comparing  the  quantity  of  the  oxygen  ab- 
sorbed with  that  of  the  hydrogen  contained  in  the  acid,  that  they  are 
exactly  in  the  proportions  for  forming  water. 

W^hen  colorless  orcin  is  exposed  together  with  ammonia  to  the  con- 
tact of  oxygen  gas,  the  beautiful  red-colored  orcein  is  produced.  Now;,, 
the  only  changes  which  take  place  here  are,  that  the  absorption  of  oxy- 
gen by  the  elements  of  orcin  and  ammonia  causes  the  formation  of 
water  ;  1  equivalent  of  orcin  C18  H12  08,  and  1  equivalent  of  ammo- 
nia NH3,  absorb  5  equivalents  of  oxygen,  and  5  equivalents  of  water 
are  produced,  the  composition  of  orcein  being  C18  HIO  08  N.  (Du- 
mas )  In  this  case  it  is  evident,  that  the  oxygen  absorbed  has  united 
merely  with  the  hydrogen.  —  L. 

28 


326  EREMACAUSIS  OR  DECAY. 

to  be  formed  in  a  manner  similar  to  the  formation  of 
acetic  acid,  by  the  eremacausis  of  saliculite  of  pot- 
ash.^ 

An  alkaline  solution  of  hsematin  being  exposed  to 
an  atmosphere  of  oxygen,  0*2  grm.  absorb  28*6  cubic 
centimeters  of  oxygen  gas  in  twenty-four  hours,  the 
alkali  acquiring  at  the  same  time  6  cubic  centimeters 
of  carbonic  acid.  (Chevreul.)  But  these  6  cubic 
centimeters  of  carbonic  acid  contain  only  an  equal 
volume  of  oxygen,  so  that  it  is  certain  from  this  ex- 
periment, that  I  of  the  oxygen  absorbed  have  not 
united  with  the  carbon.  It  is  highly  probable,  that 
during  the  oxidation  of  the  hydrogen,  a  portion  of 
the  carbon  had  united  with  the  oxygen  contained  in 
the  hsematin,  and  had  separated  from  the  other  ele- 
ments as  carbonic  acid. 

The  experiments  of  De  Saussure  upon  the  decay 
of  woody  fibre  show,  that  such  a  separation  is  quite 
possible.  Moist  woody  fibre  evolved  one  volume  of 
carbonic  acid  for  every  volume  of  oxygen  w^hich  it 
absorbed.  It  has  just  been  mentioned,  that  carbonic 
acid  contains  its  own  volume  of  oxygen.  Now, 
woody  fibre  contains  carbon  and  the  elements  of 
water,  so  that  the  result  of  the  action  of  oxygen 
upon  it  is  exactly  the  same  as  if  pure  charcoal  had 
combined  directly  with  oxygen.  But  the  characters 
of  woody  fibre  show,  that  the  elements  of  water  are 
not  contained  in  it  in  the  form  of  water  ;  for,  were 
this  the  case,  starch,  sugar,  and  gum  must  also  be 
considered  as  hydrates  of  carbon. 

But  if  the  hydrogen  does  not  exist  in  woody  fibre 
in  the  form  of  water,  the  direct  oxidation  of  the  car- 
bon cannot  be  considered  as  at  all  probable,  without 
rejecting  all  the  facts  established  by  experiment  re- 
garding the  process  of  combustion  at  low  tempera- 
tures. 


*  This  salt,  when  exposed  to  a  moist  atmosphere,  ahsorbs  3  atoms  of 
oxygen;  melanic  acid  is  produced,  a  body  resembling  humus,  in  conse- 
quence of  the  formation  of  which,  the  elements  of  1  atom  of  acetic  acid 
are  separated  from  the  saliculous  acid.  —  L. 


FORMATION  OF  CARBONIC  ACID.  327 

If  we  examine  the  action  of  oxygen  upon  a  sub- 
stance containing  a  large  quantity  of  hydrogen,,  such 
as  alcohol,  we  find  most  distinctly,  that  the  direct 
iiformation  of  carbonic  acid  is  the  last  stage  of  its 
j  oxidation,  and  that  it  is  preceded  by  a  series  of 
!  changes,  the  last  of  which  is  a  complete  combustion 
of  the  hydrogen.  Aldehyde,  acetic,  formic,  oxalic, 
and  carbonic  acids,  form  a  connected  chain  of  pro- 
ducts arising  from  the  oxidation  of  alcohol ;  and  the 
successive  changes  which  this  fluid  experiences  from 
the  action  of  oxygen  may  be  readily  traced  in  them. 
Aldehyde  is  alcohol  minus  hydrogen  ;  acetic  acid  is 
formed  by  the  direct  union  of  aldehyde  with  oxygen. 
Formic  acid  and  water  are  formed  by  the  union  of 
acetic  acid  with  oxygen.  When  all  the  hydrogen  is 
removed  from  this  formic  acid,  oxalic  acid  is  pro- 
duced ;  and  the  latter  acid  is  converted  into  car- 
bonic acid  by  uniting  with  an  additional  portion  of 
oxygen.  All  these  products  appear  to  be  formed 
simultaneously,  by  the  action  of  oxidizing  agents  on 
alcohol ;  but  it  can  scarcely  be  doubted,  that  the 
formation  of  the  last  product,  the  carbonic  acid,  does 
not  take  place  until  all  the  hydrogen  has  been  ab- 
stracted. 

The  absorption  of  oxygen  by  drying  oils  certainly 
does  not  depend  upon  the  oxidation  of  their  carbon; 
for  in  raw  nut-oil,  for  example,  which  was  not  free 
from  mucilage  and  other  substances,  only  twenty-one 
volumes  of  carbonic  acid  were  formed  for  every  146 
volumes  of  oxygen  gas  absorbed. 

It  must  be  remembered,  that  combustion  or  oxida- 
tion at  low  temperatures  produces  results  quite  simi- 
lar to  combustion  at  high  temperatures  with  limited 
access  of  air.  The  most  combustible  element  of  a 
compound,  which  is  exposed  to  the  action  of  oxygen, 
must  become  oxidized  first,  for  its  superior  combus- 
tibility is  caused  by  its  being  enabled  to  unite  with 
oxygen  at  a  temperature  at  which  the  other  elements 
cannot  enter  into  that  combination ;  this  property 
having  the  same  effect  as  a  greater  affinity. 


328  EREMACAUSIS  OR  DECAY 

The  combustibility  of  potassium  is  no  measure  of! 
its  affinity  for  oxygen ;  we  have  reason  to  believe 
that  the  attraction  of  magnesium  and  aluminium  for 
oxygen  is  greater  than  that  of  potassium  for  the 
same  element ;  but  neither  of  those  metals  oxidizes 
either  in  air  or  water  at  common  temperatures,  whilst 
potassium  decomposes  water  with  great  violence, 
and  appropriates  its  oxygen. 

Phosphorus  and  hydrogen  combine  with  oxygen  at 
ordinary  temperatures,  the  first  in  moist  air,  the 
second  when  in  contact  with  finely-divided  platinum; 
while  charcoal  requires  a  red  heat  before  it  can  enter 
into  combination  with  oxygen.  It  is  evident,  that 
phosphorus  and  hydrogen  are  more  combustible 
than  charcoal,  that  is,  that  their  affinity  for  oxygen 
at  common  temperatures  is  greater ;  and  this  is  not 
the  less  certain,  because  it  is  found,  that  carbon  in 
certain  other  conditions  shows  a  much  greater  affini- 
ty for  oxygen  than  either  of  those  substances. 

In  putrefaction,  the  conditions  are  evidently  pres- 
ent, under  which  the  affinity  of  carbon  for  oxygen 
comes  into  play;  neither  expansion,  cohesion,  nor 
the  gaseous  state,  opposes  it,  whilst  in  eremacausis 
all  these  restraints  have  to  be  overcome. 

The  evolution  of  carbonic  acid,  during  the  decay 
or  eremacausis  of  animal  or  vegetable  bodies  which 
are  rich  in  hydrogen,  must  accordingly  be  ascribed 
to  a  transposition  of  the  elements  or  disturbance  in 
their  attractions,  similar  to  that  which  gives  rise  to 
the  formation  of  carbonic  acid  in  the  processes  of 
fermentation  and  putrefaction. 

The  eremacausis  of  such  substances  is,  therefore, 
a  decomposition  analogous  to  the  putrefaction  of 
azotized  bodies.  For  in  these  there  are  two  affini- 
ties at  play;  the  affinity  of  nitrogen  for  hydrogen, 
and  that  of  carbon  for  oxygen,  and  both  facilitate  the 
disunion  of  the  elements.  Now  there  are  two  affini- 
ties also  in  action  in  those  bodies  which  decay  with 
the  evolution  of  carbonic  acid.  One  of  these  affini^ 
ties  is  the  attraction  of  the  oxygen  of  the  air  for  the 


OF  BODIES  DESTITUTE  OF  NITROGEN.  329 

hydrogen  of  the  substance,  which  corresponds  to  the 
attraction  of  nitrogen  for  the  same  element ;  and  the 
other  is  the  affinity  of  the  carbon  of  the  substance 
for  its  oxygen,  which  is  constant  under  all  circum- 
.stances. 

When  wood  putrefies  in  marshes,  carbon  and  oxy- 
gen are  separated  from  its  elements  in  the  form  of 
carbonic  acid,  and  hydrogen  in  the  form  of  carburet- 
ted  hydrogen.  But  when  wood  decays  or  putrefies 
in  the  air,  its  hydrogen  does  not  combine  with  car- 
bon, but  with  oxygen,  for  which  it  has  a  much  great- 
er affinity  at  common  temperatures. 

Now  it  is  evident,  from  the  complete  similarity  of 
these  processes,  that  decaying  and  putrefying  bodies 
can  mutually  replace  one  another  in  their  reciprocal 
actions. 

All  putrefying  bodies  pass  into  the  state  of  decay, 
when  exposed  freely  to  the  air,  and  all  decaying  mat- 
ters into  that  of  putrefaction  when  air  is  excluded. 
All  bodies,  likewise,  in  a  state  of  decay  are  capable 
of  inducing  putrefaction  in  other  bodies  in  the  same 
manner  as  putrefying  bodies  themselves  do. 


CHAPTER   VII. 

EREMACAUSIS  OR  DECAY  OF  BODIES  DESTITUTE  OF 
NITROGEN:  FORMATION  OF  ACETIC  ACID. 

All  those  substances  which  appear  to  possess  the 
property  of  entering  spontaneously  into  fermenta- 
tion and  putrefaction,  do  not  in  reality  suffer  those 
changes  without  some  previous  disturbance  in  the 
attraction  of  their  elements.  Eremacausis  always 
precedes  fermentation  and  putrefaction,  and  it  is  not 
until  after  the  absorption  of  a  certain  quantity  of 
oxygen  that  the  signs  of  a  transformation  in  the  in- 
terior of  the  substances  show  themselves. 

28* 


330  EREMACAUSIS  OR  DECAY 


It  is  a  very  general  error  to  suppose  that  organic 
substances  have  the  power  of  undergoing  change 
spontaneously,  without  the  aid  of  an  exteimal  cause. 
When  they  are  not  in  a  state  of  change,  it  is  neces- 
sary, before  they  can  assume  that  state,  that  the  ex- 
isting equilibrium  of  their  elements  should  be  dis- 
turbed ;  and  the  most  common  cause  of  this  distur- 
bance is  undoubtedly  the  atmosphere  which  surrounds 
all  bodies. 

The  juices  of  the  fruit  or  other  part  of  a  plant 
which  very  readily  undergo  decomposition,  retain 
their  properties  unchanged  as  long  as  they  are  pro- 
tected from  immediate  contact  with  the  air,  that  is, 
as  long  as  the  cells  or  organs  in  which  they  are  con- 
tained resist  the  influence  of  the  air.  It  is  not  until 
after  the  juices  have  been  exposed  to  the  air,  and 
have  absorbed  a  certain  quantity  of  oxygen,  that  the 
substances  dissolved  in  them  begin  to  be  decom- 
posed. 

The  beautiful  experiments  of  Gay-Lussac  upon 
the  fermentation  of  the  juice  of  grapes,  as  well  as 
the  important  practical  improvements  to  which  they 
have  led,  are  the  best  proofs  that  the  atmosphere 
possesses  an  influence  upon  the  changes  of  organic 
substances.  The  juice  of  grapes  which  were  ex- 
pressed under  a  receiver  filled  with  mercury,  so  that 
air  was  completely  excluded,  did  not  ferment.  But 
when  the  smallest  portion  of  air  was  introduced,  a 
certain  quantity  of  oxygen  became  absorbed,  and 
fermentation  immediately  began.  Although  the  juice 
was  expressed  from  the  grapes  in  contact  with  air, 
under  the  conditions  therefore  necessary  to  cause  its 
fermentation,  still  this  change  did  not  ensue  when 
the  juice  was  heated  in  close  vessels  to  the  tempera- 
ture of  boiling  water.  When  thus  treated,  it  could 
be  preserved  for  years  without  losing  its  property 
of  fermenting.  A  fresh  exposure  to  the  air  at  any 
period  caused  it  to  ferment. 

Animal  food  of  every  kind,  and  even  the  most 
delicate  vegetables,  may  be  preserved  unchanged  if 


OF  BODIES  DESTITUTE  OF  NITROGEN.  331 

heated  to  the  temperature  of  boiling  water  in  vessels 
from  which  the  air  is  completely  excluded.  Food 
thus  prepared  has  been  kept  for  fifteen  years,  and 
upon  opening  the  vessels,  after  this  long  time,  has 
been  found  as  fresh  and  well-flavoured  as  when  origi- 
nally placed  in  them.* 

The  action  of  the  oxygen  in  these  processes  of 
decomposition  is  very  simple ;  it  excites  changes  in 
the  composition  of  the  azotized  matters  dissolved  in 
the  juices,  —  the  mode  of  combination  of  the  elements 
of  those  matters  undergoes  a  disturbance  and  change 
in  consequence  of  their  contact  with  oxygen.  The 
oxygen  acts  here  in  a  similar  manner  to  the  friction 
or  motion  which  affects  the  mutual  decomposition  of 
two  salts,  the  crystallization  of  salts  from  their 
solution,  or  the  explosion  of  fulminating  mercury. 
It  causes  the  state  of  rest  to  be  converted  into  a 
state  of  motion. 

When  this  condition  of  intestine  motion  is  once 
excited,  the  presence  of  oxygen  is  no  longer  neces- 
sary. The  smallest  particle  of  an  azotized  body  in 
this  act  of  decomposition  exercises  an  influence  upon 
the  particles  in  contact  with  it,  and  the  state  of 
motion  is  thus  propagated  through  the  substance. 
The  air  may  now  be  completely  excluded,  but  the 

*  The  process  is  as  follows :  Let  the  substance  to  be  preserved  be 
first  parboiled,  or  rather  somewhat  more,  the  bones  of  the  meat  being 
previously  removed.  Put  the  meat  into  a  tin  cylinder,  fill  up  the 
vessel  with  seasoned  rich  soup,  and  then  solder  on  the  lid,  pierced 
with  a  small  hole.  When  this  has  been  done,  let  the  tin  vessel  thus 
prepared  be  placed  in  brine  and  heated  to  the  boiling  point,  to  com- 
plete the  cooking  of  the  meat.  The  hole  of  the  lid  is  now  to  be  closed 
by  soldering,  whilst  the  air  is  rarefied.  The  vessel  is  then  allowed  to 
cool,  and  from  the  diminution  of  volume,  in  consequence  of  the  re- 
duction of  temperature,  both  ends  of  the  cylinder  are  pressed  inwards 
and  become  concave.  The  tin  cases,  thus  hermetically  sealed,  are  ex- 
posed in  a  test-chamber,  for  at  least  a  month,  to  a  temperature  above 
what  they  are  ever  likely  to  encounter;  from  90°  to  110°  F.  If  the 
process  has  failed,  putrefaction  takes  place,  and  gas  is  evolved,  which 
will  cause  the  ends  of  the  case  to  bulge,  so  as  to  render  them  convex, 
instead  of  concave.  But  the  contents  of  those  cases  which  stand  the 
test  will  infallibly  keep  perfectly  sweet  and  good  in  any  climate,  and 
for  any  number  of  years.  If  there  be  any  taint  about  the  meat  when 
put  up,  it  inevitably  ferments,  and  is  detected  in  the  proving  process. 
—  Ure's  Diet,  of  Arts  and  Manuf. 


332  EREMACAUSIS  OR  DECAY 

fermentation  or  putrefaction  proceeds  uninterrupted- 
ly to  its  completion.  It  has  been  remarked,  that  the 
mere  contact  of  carbonic  acid  is  sufficient  to  produce 
fermentation  in  the  juices  of  several  fruits. 

The  contact  of  ammonia  and  alkalies  in  general 
may  be  mentioned  amongst  the  chemical  conditions, 
which  determine  the  commencement  of  eremacausis ; 
for  their  presence  causes  many  substances  to  absorb 
oxygen  and  to  decay,  in  which  neither  oxygen  nor 
alkalies  alone  produce  that  change. 

Thus  alcohol  does  not  combine  with  the  oxygen 
of  the  air  at  common  temperatures.  But  a  solution 
of  potash  in  alcohol  absorbs  oxygen  with  much 
rapidity,  and  acquires  a  brown  color.  The  alcohol  is 
found  after  a  short  time  to  contain  acetic  acid,  form- 
ic acid,  and  the  products  of  the  decomposition  of 
aldehyde  by  alkalies,  including  aldehyde  resin,  which 
gives  the  liquid  a  brown  color. 

The  most  general  condition  for  the  production  of 
eremacausis  in  organic  matter  is  contact  with  a  body 
already  in  the  state  of  eremacausis  or  putrefaction. 
We  have  here  an  instance  of  true  contagion ;  for 
the  communication  of  the  state  of  combustion  is  in 
reality  the  effect  of  the  contact. 

It  is  decaying  wood  which  causes  fresh  wood  around 
it  to  assume  the  same  condition,  and  it  is  the  very 
finely  divided  woody  fibre  in  the  act  of  decay  which 
in  moistened  gall-nuts  converts  the  tannic  acid  with 
such  rapidity  into  gallic  acid. 

A  most  remarkable  and  decided  example  of  this 
induction  of  combustion  has  been  observed  by  De 
Saussure.  It  has  already  been  mentioned,  that  moist 
woody  fibre,  cotton,  silk,  or  vegetable  mould,  in  the 
act  of  fermentation  or  putrefaction,  converts  oxygen 
gas  which  may  surround  it  into  carbonic  acid,  with- 
out change  of  volume.  Now,  De  Saussure  added 
a  certain  quantity  of  hydrogen  gas  to  the  oxygen, 
and  observed  a  diminution  in  volume  immediately 
after  the  addition.  A  part  of  the  hydrogen  gas  had 
disappeared,  and  along  with  it  a  portion  of  the  oxy- 


OF  BODIES  DESTITUTE  OF  NITROGEN.  333 

gen,  but  a  corresponding  quantity  of  carbonic  acid 
gas  had  not  been  formed.  The  hydrogen  and  oxy- 
gen had  disappeared  in  exactly  the  same  proportion 
as  that  in  which  they  combine  to  form  water ;  a  true 
combustion  of  the  hydrogen,  therefore,  had  been  in- 
duced by  mere  contact  with  matter  in  the  state  of 
eremacausis.  The  action  of  the  decaying  substance 
here  produced  results  exactly  similar  to  those  effect- 
ed by  spongy  platinum ;  but  that  they  proceeded 
from  a  different  cause  was  shown  by  the  fact  that 
the  presence  of  carbonic  oxide,  w^hich  arrests  com- 
pletely the  action  of  platinum  on  carburetted  hydro- 
gen, did  not  retard  in  the  slightest  degree  the  com- 
bustion of  the  hydrogen  in  contact  with  the  decaying 
bodies. 

But  the  same  bodies  were  found  by  De  Saussure 
not  to  possess  the  property  just  described,  before 
they  were  in  a  state  of  fermentation  or  decay  ;  and 
he  has  shown  that  even  when  they  are  in  this  state, 
the  presence  of  antiseptic  matter  destroys  completely 
all  their  influence. 

Let  us  suppose  a  volatile  substance  containing  a 
large  quantity  of  hydrogen  to  be  substituted  for  the 
hydrogen  gas  in  De  Saussure's  experiments.  Now, 
the  hydrogen  in  such  compounds  being  contained  in 
a  state  of  greater  condensation  would  suffer  a  more 
rapid  oxidation,  that  is,  its  combustion  would  be 
sooner  completed.  This  principle  is  in  reality  at- 
tended to  in  the  manufactories  in  which  acetic  acid 
is  prepared  according  to  the  new  plan.  In  the  pro- 
cess there  adopted  all  the  conditions  are  afforded 
for  the  eremacausis  of  alcohol,  and  for  its  consequent 
conversion  into  acetic  acid. 

The  alcohol  is  exposed  to  a  moderate  heat,  and 
spread  over  a  very  extended  surface,  but  these  con- 
ditions are  not  sufficient  to  effect  its  oxidation. 
The  alcohol  must  be  mixed  with  a  substance  which 
is  with  facility  changed  by  the  oxygen  of  the  air, 
and  either  enters  into  eremacausis  by  mere  contact 
with   oxygen,  or  by  its  fermentation  or  putrefaction 


334  EREMACAUSIS  OR  DECAY 

yields  products  possessed  of  this  property.  A  small 
quantity  of  beer,  acescent  wine,  a  decoction  of  malt, 
honey,  and  numerous  other  substances  of  this  kind, 
possess  the  action  desired. 

The  difference  in  the  nature  of  the  substances 
which  possess  this  property  shows,  that  none  of 
them  can  contain  a  peculiar  matter  which  has  the 
property  of  exciting  eremacausis  ;  they  are  only  the 
bearers  of  an  action,  the  influence  of  which  extends 
beyond  the  sphere  of  its  own  attractions.  Their 
power  consists  in  a  condition  of  decomposition  or 
eremacausis,  which  impresses  the  same  condition 
upon  the  atoms  of  alcohol  in  its  vicinity ;  exactly  as 
in  the  case  of  an  alloy  of  platinum  and  silver  dis- 
solving in  nitric  acid,  in  which  the  platinum  becomes 
oxidized,  by  virtue  of  an  inductive  action  exercised 
upon  it  by  the  silver  in  the  act  of  its  oxidation. 
The  hydrogen  of  the  alcohol  is  oxidized  at  the 
expense  of  the  oxygen  in  contact  with  it,  and  forms 
water,  evolving  heat  at  the  same  time ;  the  residue 
is  aldehyde,  a  substance  which  has  as  great  an  affin- 
ity for  oxygen  as  sulphurous  acid,  and  combines, 
therefore,  directly  with  it,  producing  acetic  acid. 


CHAPTER   VIIL 

EREMACAUSIS  OF  SUBSTANCES  CONTAINING  NITROGEN. 

NITRIFICATION. 

When  azotized  substances  are  burned  at  high 
temperatures,  their  nitrogen  does  not  enter  into 
direct  combination  with  oxygen.  The  knowledge 
of  this  fact  is  of  assistance  in  considering  the  pro- 
cess of  the  eremacausis  of  such  substances.  Azotized 
organic  matter  always  contains  carbon  and  hydrogen, 
both  of  which  elements  have  a  very  strong  affinity 
for  oxygen. 

Now   nitrogen  possesses  a  very  feeble  affinity  for 


OF  BODIES  CONTAINING  NITROGEN.  335 

that  element,  so  that  its  compounds  during  their 
combustion  present  analogous  phenomena  to  those 
which  are  observed  in  the  combustion  of  substances 
containing  a  large  proportion  of  hydrogen  and  car- 
bon ;  a  separation  of  the  carbon  of  the  latter  sub- 
stances in  an  uncombined  state  takes  place,  and  in 
the  same  way  the  substances  containing  nitrogen 
give  out  that  element  in  its  gaseous  form. 

When  a  moist  azotized  animal  matter  is  exposed 
to  the  action  of  the  air,  ammonia  is  always  liberated ; 
nitric  acid  is  never  formed. 

But  when  alkalies  or  alkaline  bases  are  present,  a 
union  of  oxygen  with  the  nitrogen  takes  place  under 
the  same  circumstances,  and  nitrates  are  formed 
together  with  the  other  products  of  oxidation. 

Although  we  see  the  most  simple  means  and  direct 
methods  employed  in  the  great  processes  of  decom- 
position which  proceed  in  nature,  still  we  find  that 
the  final  result  depends  on  a  succession  of  actions, 
which  are  essentially  influenced  by  the  chemical 
nature  of  the  bodies  submitted  to  decomposition. 

When  it  is  observed  that  the  character  of  a  sub- 
stance remains  unaltered  in  a  whole  series  of  phe- 
nomena, there  is  no  reason  to  ascribe  a  new  charac- 
ter to  it,  for  the  purpose  of  explaining  a  single 
phenomenon,  especially  where  the  explanation  of 
that  according  to  known  facts  offers  no  difficulty. 

The  most  distinguished  philosophers  suppose  that 
the  nitrogen  in  an  animal  substance,  when  exposed 
to  the  action  of  air,  water,  and  alkaline  bases, 
obtains  the  power  to  unite  directly  with  oxygen,  and 
form  nitric  acid,  but  we  are  not  acquainted  with  a 
single  fact  which  justifies  this  opinion.  It  is  only 
by  the  interposition  of  a  large  quantity  of  hydrogen 
in  the  state  of  combustion  or  oxidation,  that  nitro- 
gen can  be  converted  into  an  oxide. 

When  a  compound  of  nitrogen  and  carbon,  such 
as  cyanogen,  is  burned  in  oxygen  gas,  its  carbon 
alone  is  oxidized;  and  when  it  is  conducted  over  a 
metallic  oxide  heated  to  redness,  an  oxide  of  nitro- 


336  EREMACAUSIS  OR  DECAY 

gen  is  very  rarely  produced,  and  never  when  the 
carbon  is  in  excess.  Kuhlmann  found  in  his  experi- 
ments, that  it  was  only  when  cyanogen  was  mixed 
with  an  excess  of  oxygen  gas,  and  conducted  over 
spongy  platinum,  that  nitric  acid  was  generated. 

Kuhlmann  could  not  succeed  in  causing  pure  nitro- 
gen to  combine  directly  with  oxygen,  even  under 
the  most  favorable  circumstances;  thus,  with  the 
aid  of  spongy  platinum  at  different  temperatures,  no 
union  took  place. 

The  carbon  in  the  cyanogen  gas  must,  therefore, 
have  given  rise  to  the  combustion  of  the  nitrogen  by 
induction. 

On  the  other  hand  we  find  that  ammonia  (a  com- 
pound of  hydrogen  and  nitrogen)  cannot  be  exposed 
to  the  action  of  oxygen^  without  the  formation  of  an 
oxide  of  nitrogen,  and  in  con&equence  the  production 
of  nitric  acid.  ^ 

It  is  owing  to  the  great  facility  with  which  ammo- 
nia is  converted  into  nitric  acid,  that  it  is  so  difficult 
to  obtain  a  correct  determination  of  the  quantity  of 
nitrogen  in  a  compound  subjected  to  analysis,  in 
which  it  is  either  contained  in  the  form  of  ammonia, 
or  from  which  ammonia  is  formed  by  an  elevation  of 
temperature.  For  when  ammonia  is  passed  over 
red-hot  oxide  of  copper,  it  is  converted,  either  com- 
pletely or  partially,  into  binoxide  of  nitrogen. 

When  ammoniacal  gas  is  conducted  over  peroxide 
of  manganese  or  iron  heated  to  redness,  a  large 
quantity  of  nitrate  of  ammonia  is  obtained,  if  the 
ammonia  be  in  excess ;  and  the  same  decomposition 
happens  w^hen  ammonia  and  oxygen  are  together 
passed  over  red-hot  spongy  platinum. 

It  appears,  therefore,  that  the  combination  of 
oxygen  with  nitrogen  occurs  rarely  during  the  com- 
bustion of  compounds  of  the  latter  element  with 
carbon,  but  that  nitric  acid  is  always  a  product  when 
ammonia  is  present  in  the  substance  exposed  to 
oxidation. 

The   cause   wherefore   the   nitrogen   in   ammonia 


OF  BODIES  CONTAINING  NITROGEN.  337 

exhibits  such  a  strong  disposition  to  become  con- 
verted into  nitric  acid  is,  undoubtedly,  that  the  two 
products,  which  are  the  result  of  the  oxidation  of 
the  constituents  of  ammonia,  possess  the  power  of 
uniting  with  one  another.  Now  this  is  not  the  case 
in  the  combustion  of  compounds  of  carbon  and 
nitrogen;  here  one  of  the  products  is  carbonic  acid, 
which,  on  account  of  its  gaseous  form,  must  oppose 
the  combination  of  the  oxygen  and  nitrogen,  by 
preventing  their  mutual  contact,  while  the  superior 
affinity  of  its  carbon  for  the  oxygen  during  the  act 
of  its  formation  will  aid  this  effect. 

When  sufficient  access  of  air  is  admitted  during 
the  combustion  of  ammonia,  water  is  formed  as  well 
as  nitric  acid,  and  both  of  these  bodies  combine 
together.  The  presence  of  water  may,  indeed,  be 
considered  as  one  of  the  conditions  essential  to 
nitrification,  since  nitric  acid  cannot  exist  without  it. 

Eremacausis  is  a  kind  of  putrefaction,  differing 
from  the  common  process  of  putrefaction,  only  in 
the  part  which  the  oxygen  of  the  air  plays  in  the 
transformations  of  the  body  in  decay.  When  this  is 
remembered,  and  when  it  is  considered  that  in  the 
transposition  of  the  elements  of  azotized  bodies 
their  nitrogen  assumes  the  form  of  ammonia,  and 
that  in  this  form,  nitrogen  possesses  a  much  greater 
disposition  to  unite  with  oxygen  than  it  has  in  any  of 
its  other  compounds  ;  we  can  with  difficulty  resist  the 
conclusion,  that  ammonia  is  the  general  cause  of 
nitrification  on  the  surface  of  the  earth. 

Azotized  animal  matter  is  not,  therefore,  the  im- 
mediate cause  of  nitrification ;  it  contributes  to  the 
production  of  nitric  acid  only  in  so  far  as  it  is  a 
slow  and  continued  source  of  ammonia. 

Now  it  has  been  shown  in  the  former  part  of  this 
work,  that  ammonia  is  always  present  in  the  atmo- 
sphere, so  that  nitrates  might  thence  be  formed  in 
substances  which  themselves  contained  no  azotized 
matter.  It  is  known,  also,  that  porous  substances 
possess  generally  the  power  of  condensing  ammonia;, 

29 


338  VINOUS  FERMENTATION. 

there  are  few  ferruginous  earths  which  do  not  evolve 
ammoniacal  products  when  heated  to  redness,  and 
ammonia  is  the  cause  of  the  peculiar  smell  perceived 
upon  moistening  aluminous  minerals.  Thus,  ammo- 
nia, by  being  a  constituent  of  the  atmosphere,  is  a 
very  widely  diffused  cause  of  nitrification,  which 
will  come  into  play  whenever  the  different  conditions 
necessary  for  the  oxidation  of  ammonia  are  com- 
bined. It  is  probable,  that  other  organic  bodies  in 
the  state  of  eremacausis  are  the  means  of  causing 
the  combustion  of  ammonia ;  at  all  events,  the  cases 
are  very  rare,  in  which  nitric  acid  is  generated  from 
ammonia,  in  the  absence  of  all  matter  capable  of 
eremacausis. 

From  the  preceding  observations  on  the  causes  of 
fermentation,  putrefaction,  and  decay,  we  may  now 
draw  several  conclusions  calculated  to  correct  the 
views  generally  entertained  respecting  the  fermenta- 
tion of  wine  and  beer,  and  several  other  important 
processes  of  decomposition  which  occur  in  nature. 


CHAPTER   IX. 

ON  VINOUS  FERMENTATION:  — WINE  AND  BEER. 

It  has  already  been  mentioned,  that  fermentation 
is  excited  in  the  juice  of  grapes  by  the  access  of  air ; 
alcohol  and  carbonic  acid  being  formed  by  the  de- 
composition of  the  sugar  contained  in  the  fluid.  But 
it  was  also  stated,  that  the  process  once  commenced, 
continues  until  all  the  sugar  is  completely  decom- 
posed, quite  independently  of  any  further  influence 
of  the  air. 

In  addition  to  the  alcohol  and  carbonic  acid  formed 
by  the  fermentation  of  the  juice,  there  is  also  pro- 
duced a  yellow  or  gray  insoluble  substance,  contain- 
ing a  large  quantity  of  nitrogen.  It  is  this  body 
which  possesses  the  power  of  inducing  fermentation 


YEAST  FEOM  BEER  AND  WTNE.  339 

in  a  new  solution  of  sugar,  and  which  has  in  conse- 
quence received  the  name  of  ferment. 

The  alcohol  and  carbonic  acid  are  produced  from 
the  elements  of  the  sugar,  and  the  ferment  from  those 
azotized  constituents  of  the  grape-juice,  which  have 
been  termed  gluten,  or  vegetable  albumen. 

According  to  the  experiments  of  De  Saussure, 
fresh  impure  gluten  evolved,  in  five  weeks,  twenty- 
eight  times  its  volume  of  a  gas  which  consisted  |  of 
carbonic  acid,  and  \  of  pure  hydrogen  gas ;  ammo- 
niacal  salts  of  several  organic  acids  were  formed  at 
the  same  time.  Water  must,  therefore,  be  decom- 
posed during  the  putrefaction  of  gluten ;  the  oxygen 
of  this  water  must  enter  into  combination  with  some 
of  its  constituents,  whilst  hydrogen  is  liberated,  a 
circumstance  which  happens  only  in  decompositions 
of  the  most  energetic  kind.  Neither  ferment  nor 
any  substance  similar  to  it  is  formed  in  this  case ; 
and  we  have  seen  that  in  the  fermentation  of  sac- 
charine vegetable  juices,  no  escape  of  hydrogen  gas 
takes  place. 

It  is  evident,  that  the  decomposition  which  gluten 
suffers  in  an  isolated  state,  and  that  which  it  under- 
goes when  dissolved  in  a  vegetable  juice,  belong  to 
two  different  kinds  of  transformations.  There  is 
reason  to  believe,  that  its  change  to  the  insoluble 
state  depends  upon  an  absorption  of  oxygen,  for  its 
separation  in  this  state  may  be  effected,  under  cer- 
tain conditions,  by  free  exposure  to  the  air,  without 
the  presence  of  fermenting  sugar.  It  is  known  also 
that  the  juice  of  grapes,  or  vegetable  juices  in  gen- 
eral, become  turbid  when  in  contact  with  air,  before 
fermentation  commences;  and  this  turbidness  is  owing 
to  the  formation  of  an  insoluble  precipitate  of  the 
same  nature  as  ferment. 

From  the  phenomena  which  have  been  observed 
during  the  fermentation  of  wort,*  it  is  known  with 

*  Wort  is  an  infusion  of  malt ;  it  consists  of  the  soluble  parts  of  this 
substance  dissolved  in  water.  —  Ed. 


340  VINOUS  FERMENTATION. 

perfect  certainty,  that  ferment  is  formed  from  gluten 
at  the  same  time  that  the  transformation  of  the  sugar 
is  effected ;  for  the  wort  contains  the  azotized  mat- 
ter of  the  corn,  namely,  gluten  in  the  same  condition 
as  it  exists  in  the  juice  of  grapes.  The  wort  fer- 
ments by  the  addition  of  yeast,  but  after  its  decom- 
position is  completed,  the  quantity  of  ferment  or 
yeast  is  found  to  be  thirty  times  greater  than  it  was 
originally. 

Yeast  from  beer  and  that  from  wine,  examined  un- 
der the  microscope,  present  the  same  form  and  gen- 
eral appearance.  They  are  both  acted  on  in  the 
same  manner  by  alkalies  and  acids,  and  possess  the 
power  of  inducing  fermentation  anew  in  a  solution 
of  sugar;  in  short,  they  must  be  considered  as 
identical. 

The  fact  that  water  is  decomposed  during  the  pu- 
trefaction of  gluten  has  been  completely  proved.  The 
tendency  of  the  carbon  of  the  gluten  to  appropriate 
the  oxygen  of  water  must  also  always  be  in  action, 
whether  the  gluten  is  decomposed  in  a  soluble  or  in- 
soluble state.  These  considerations,  therefore,  as  well 
as  the  circumstance  which  all  the  experiments  made 
on  this  subject  appear  to  point  out,  that  the  conver- 
sion of  gluten  to  the  insoluble  state  is  the  result  of 
oxidation,  lead  us  to  conclude,  that  the  oxygen  con- 
sumed in  this  process  is  derived  from  the  elements 
of  water,  or  from  the  sugar  which  contains  oxygen 
and  hydrogen  in  the  same  proportion-  as  water.  At 
all  events,  the  oxygen  thus  consumed  in  the  fermen- 
tation of  wine  and  beer  is  not  taken  from  the  at- 
mosphere. 

The  fermentation  of  pure  sugar  in  contact  with 
yeast  must  evidently  be  a  very  different  process  from 
the  fermentation  of  wort  or  must,* 

In  the  former  case,  the  yeast  disappears  during 
the  decomposition  of  sugar;  but  in  the  latter,  a 
transformation  of  gluten  is  effected  at  the  same  time, 

■*  The  liquid  expressed  from  grapes  when  fully  ripe  is  called  must. 


OILY  AND  ETHEREAL  PRODUCTS.  341 

by  which  ferment  is  generated.  Thus  yeast  is  de- 
stroyed in  the  one  case,  but  is  formed  in  the  other. 

Now  since  no  free  hydrogen  gas  can  be  detected 
during  the  fermentation  of  beer  and  wine,  it  is  evi- 
dent that  the  oxidation  of  the  gluten,  that  is,  its 
conversion  into  ferment,  must  take  place  at  the  cost 
either  of  the  oxygen  of  the  water,  or  of  that  of  the 
sugar ;  whilst  the  hydrogen  which  is  set  free  must 
enter  into  new  combinations,  or  by  the  deoxidation 
of  the  sugar,  new  compounds  containing  a  large  pro- 
portion of  hydrogen,  and  small  quantity  of  oxygen, 
together  with  the  carbon  of  the  sugar,  must  be 
formed. 

It  is  well  known,  that  wine  and  fermented  liquors 
generally  contain,  in  addition  to  the  alcohol,  other 
substances  which  could  not  be  detected  before  their 
fermentation,  and  which  must  have  been  formed, 
therefore,  during  that  process  in  a  manner  similar  to 
the  production  of  mannite.  The  smell  and  taste 
"which  distinguish  wine  from  all  other  fermented 
liquids  are  known  to  depend  upon  an  ether  of  a  vol- 
atile and  highly  combustible  acid  ;  the  ether  is  of  an 
oily  nature,  and  has  received  the  name  (Enanthic 
ether.  It  is  also  ascertained,  that  the  smell  and 
taste  of  brandy  from  corn  and  potato  are  owing  to  a 
peculiar  oil,  the  oil  of  potatoes.  This  oil  is  more 
closely  allied  to  alcohol  in  its  properties,  than  to 
any  other  organic  substance. 

These  bodies  are  products  of  the  deoxidation  of 
the  substances  dissolved  in  the  fermenting  liquids ; 
they  contain  less  oxygen  than  sugar  or  gluten,  but 
are  remarkable  for  the  large  quantity  of  hydrogen 
which  enters  into  their  composition. 

(Enanthic  acid  contains  an  equal  number  of  equiv- 
alents of  carbon  and  hydrogen,  exactly  the  same 
proportions  of  these  elements,  therefore,  as  sugar, 
but  by  no  means  the  same  proportion  of  oxygen. 
The  oil  of  potatoes  contains  much  more  hydrogen. 

Although  it  cannot  be  doubted,  that  these  volatile 
liquids   are   formed  by  a  mutual  interchange  of  the 

29* 


344  VINOUS  FERMENTATION. 

various  modifications  in  the  nature  of  the  products 
generated. 

Whatever  opinion,  however,  may  be  held  regard- 
ing the  origin  of  the  volatile  odoriferous  substances 
obtained  in  the  fermentation  of  wine,  it  is  quite  cer- 
tain that  the  characteristic  smell  of  wine  is  owing 
to  an  ether  of  an  organic  acid,  resembling  one  of  the 
fatty  acids  (oenanthic  ether). 

It  is  only  in  liquids  which  contain  other  very  solu- 
ble acids,  that  the  fatty  acids  and  cenanthic  acids  are 
capable  of  entering  into  combination  with  the  ether 
of  alcohol,  and  of  thus  producing  compounds  of  a 
peculiar  smell.  This  ether  is  found  in  all  wines 
which  contain  free  acid,  and  is  absent  from  those  in 
which  no  acids  are  present.  This  acid,  therefore,  is 
the  means  by  which  the  smell  is  produced ;  since 
without  its  presence  cenanthic  ether  could  not  be 
formed. 

The  greatest  part  of  the  oil  of  brandy  made  from 
corn  consists  of  a  fatty  acid  not  converted  into 
ether;  it  dissolves  oxide  of  copper  and  metallic  ox- 
ides in  general,  and  combines  with  the  alkalies. 

The  principal  constituent  of  this  oil  is  an  acid 
identical  in  composition  with  oenanthic  acid,  but 
different  in  properties.  (Mulder.)  It  is  formed  in 
fermenting  liquids,  which,  if  they  be  acid,  contain 
only  acetic  acid,  a  body  which  has  no  influence  in 
causing  other  acids  to  form  ethers. 

The  oil  of  brandy  made  from  potatoes  is  the  hy- 
drate of  an  organic  base  analogous  to  ether,  and 
capable,  therefore,  of  entering  into  combination  with 
acids.  It  is  formed  in  considerable  quantity  in  fer- 
menting liquids  which  are  slightly  alkaline;  under 
circumstances,  consequently,  in  which  it  is  incapable 
of  combining  with  an  acid. 

The  products  of  the  fermentation  and  putrefaction 
of  neutral  vegetable  and  animal  matters  are  gener- 
ally accompanied  by  substances  of  an  oflfensive  odor; 
but  the  most  remarkable  example  of  the  generation 
of  a  true  ethereal  oil  is  seen  in  the  fermentation  of 


ODORIFEROUS  PRODUCTS.  345 

the  Herha  centaurium  minorius,  a  plant  which  pos- 
sesses no  smell.  When  it  is  exposed  in  water  to  a 
slightly  elevated  temperature  it  ferments,  and  emits 
an  agreeable  penetrating  odor.  By  the  distillation 
of  the  liquid,  an  ethereal  oily  substance  of  great  vola- 
tility is  obtained,  which  excites  a  pricking  sensation 
in  the  eyes,  and  a  flow  of  tears.    (Biichner.) 

The  leaves  of  the  tobacco  plant  present  the  same 
phenomena;  when  fresh  they  possess  very  little  or 
no  smell.  When  they  are  subjected  to  distillation 
with  water,  a  weak  ammoniacal  liquid  is  obtained, 
upon  which  a  fatty  crystallizable  substance  swims, 
w^hich  does  not  contain  nitrogen,  and  is  quite  desti- 
tute of  smell.  But  w^hen  the  same  plant,  after  being 
dried,  is  moistened  with  water,  tied  together  in  small 
bundles,  and  placed  in  heaps,  a  peculiar  process  of 
decomposition  takes  place.  Fermentation  com- 
mences, and  is  accompanied  by  the  absorption  of 
oxygen ;  the  leaves  now  become  w^arm  and  emit  the 
characteristic  smell  of  prepared  tobacco  and  snufF. 
When  the  fermentation  is  carefully  promoted  and 
too  high  a  heat  avoided,  this  smell  increases  and  be- 
comes more  delicate;  and  after  the  fermentation  is 
completed,  an  oily  azotized  volatile  matter  called 
nicotine  is  found  in  the  leaves.  This  substance, 
—  nicotine,  which  possesses  all.  the  properties  of  a 
base,  was  not  present  before  the  fermentation.  The 
different  kinds  of  tobacco  are  distinguished  from  one 
another,  like  wines,  by  having  very  diff*erent  odori- 
ferous substances,  which  are  generated  along  with 
the  nicotine. 

We  know,  that  most  of  the  blossoms  and  vegetable 
substances  which  possess  a  smell  owe  this  property 
to  a  volatile  oil  existing  in  them;  but  it  is  not  less 
certain,  that  others  emit  a  smell  only  when  they 
undergo  change  or  decomposition. 

Arsenic  and  arsenious  acid  are  both  quite  inodor- 
ous. It  is  only  during  their  oxidation  that  they  emit 
their  characteristic  odor  of  garlic.  The  oil  of  the 
berries  of  the  elder-tree,  many  kinds  of  oil  of  turpen-. 


346  VINOUS  FERMENTATION. 

tine,  and  oil  of  lemons,  possess  a  smell  only  during 
their  oxidation  or  decay.  The  same  is  the  case  with 
many  blossoms;  and  Geiger  has  shown,  that  the 
smell  of  musk  is  owing  to  its  gradual  putrefaction 
and  decay. 

It  is  also  probable,  that  the  peculiar  odorous  prin- 
ciple of  many  vegetable  substances  is  newly  formed 
during  the  fermentation  of  the  saccharine  juices  of 
the  plants.  At  all  events,  it  is  a  fact,  that  very 
small  quantities  of  the  blossoms  of  the  violet,  elder, 
linden,  or  cowslip,  added  to  a  fermenting  liquid,  are 
sufficient  to  communicate  a  very  strong  taste  and 
smell,  which  the  addition  of  the  water  distilled  from 
a  quantity  a  hundred  times  greater  would  not  effect. 
The  various  kinds  of  beer  manufactured  in  Bavaria 
are  distinguished  by  different  flavors,  which  are 
given  by  allowing  small  quantities  of  the  herbs  and 
blossoms  of  particular  plants  to  ferment  along  with 
the  wort.  On  the  Rhine,  also,  an  artificial  bouquet 
is  often  given  to  wine  for  fraudulent  purposes,  by  the 
addition  of  several  species  of  the  sage  and  rue  to 
the  fermenting  liquor ;  but  the  fictitious  perfume 
thus  obtained  differs  from  the  genuine  aroma,  by  its 
inferior  durability,  and  by  being  gradually  dissi- 
pated. 

The  juice  of  grapes  grown  in  different  climates 
differs  not  only  in  the  proportion  of  free  acid  which 
it  contains,  but  also  in  respect  to  the  quantity  of 
sugar  dissolved  in  it.  The  quantity  of  azotized 
matter  in  the  juice  seems  to  be  the  same  in  whatever 
parts  the  grapes  may  grow ;  at  least  no  difference 
has  been  observed  in  the  amount  of  yeast  formed 
during  fermentation  in  the  south  of  France,  and  on 
the  Rhine. 

The  grapes  grown  in  hot  climates,  as  well  as  the 
boiled  juice  obtained  from  them,  are  proportionally 
rich  in  sugar.  Hence,  during  the  fermentation  of 
the  juice,  the  complete  decomposition  of  its  azotized 
matters,  and  their  separation  in  the  insoluble  state, 
are  effected  before  all  the  sugar  has  been   converted 


VAEIOUS  PROPERTIES  OF  WINES.  ^  347 

into  alcohol  and  carbonic  acid.  A  certain  quantity 
of  the  sugar  consequently  remains  mixed  with  the 
wine  in  an  undecomposed  state,  the  condition  neces- 
sary for  its  further  decomposition  being  absent. 

The  azotized  matters  in  the  juice  of  grapes  of  the 
temperate  zones,  on  the  contrary,  are  not  completely 
separated  in  the  insoluble  state,  when  the  entire 
transformation  of  the  sugar  is  effected.  The  wine 
of  these  grapes,  therefore,  does  not  contain  sugar, 
but  variable  quantities  of  undecomposed  gluten  in 
solution. 

This  gluten  gives  the  wine  the  property  of  becom- 
ing spontaneously  converted  into  vinegar,  when  the 
access  of  air  is  not  prevented.  For  it  absorbs 
oxygen  and  becomes  insoluble;  and  its  oxidation  is 
communicated  to  the  alcohol,  which  is  converted 
into  acetic  acid. 

By  allowing  the  wine  to  remain  at  rest  in  casks 
with  a  very  limited  access  of  air,  and  at  the  lowest 
possible  temperature,  the  oxidation  of  this  azotized 
matter  is  effected  without  the  alcohol  undergoing 
the  same  change,  a  higher  temperature  being  neces- 
sary to  enable  alcohol  to  combine  with  oxygen.  As 
long  as  the  wine  in  ihe  stilling-casks  deposites  yeast, 
it  can  still  be  caused  to  ferment  by  the  addition  of 
sugar,  but  old  well-layed  wine  has  lost  this  property, 
because  the  condition  necessary  for  fermentation, 
namely,  a  substance  in  the  act  of  decomposition  or 
putrefaction,  is  no  longer  present  in  it. 

In  hotels  and  other  places  where  wine  is  drawn 
gradually  from  a  cask,  and  a  proportional  quantity 
of  air  necessarily  introduced,  its  eremacausis,  that 
is,  its  conversion  into  acetic  acid,  is  prevented  by 
the  addition  of  a  small  quantity  of  sulphurous  acid. 
This  acid,  by  entering  into  combination  with  the 
oxygen  of  the  air  contained  in  the  cask,  or  dissolved 
in  the  wine,  prevents  the  oxidation  of  the  organic 
matter. 

The  various  kinds  of  beer  differ  from  one  another 
in  the  same  way  as  the  wines. 


348  FERMENTATION  OF  BEER. 

English,  French,  and  most  of  the  German  beers, 
are  converted  into  vinegar  when  exposed  to  the 
action  of  air.  But  this  property  is  not  possessed  by 
Bavarian  beer,  which  may  be  kept  in  vessels  only 
half-filled  without  acidifying  or  experiencing  any 
change.  This  valuable  quality  is  obtained  for  it  by 
a  peculiar  management  of  the  fermentation  of  the 
wort.  The  perfection  of  experimental  knowledge 
has  here  led  to  the  solution  of  one  of  the  most  beau- 
tiful problems  of  the  theory  of  fermentation. 

Wort  is  proportionally  richer  in  gluten  than  in 
sugar,  so  that  during  its  fermentation  in  the  common 
way,  a  great  quantity  of  yeast  is  formed  as  a  thick 
scum.  The  carbonic  acid  evolved  during  the  process 
attaches  itself  to  the  particles  of  yeast,  by  which 
they  become  specifically  lighter  than  the  liquid  in 
which  they  are  formed,  and  rise  to  its  surface.  Glu- 
ten in  the  act  of  oxidation  comes  in  contact  with 
the  particles  of  the  decomposing  sugar  in  the  inte- 
rior of  the  liquid.  The  carbonic  acid  from  the  sugar 
and  insoluble  ferment  from  the  gluten  are  disengaged 
simultaneously,  and  cohere  together. 

A  great  quantity  of  gluten  remains  dissolved  in 
the  fermented  liquid,  even  after  the  transformation 
of  the  sugar  is  completed,  and  this  gluten  causes 
the  conversion  of  the  alcohol  into  acetic  acid,  on 
account  of  its  strong  disposition  to  attract  oxygen, 
and  to  undergo  decay.  Now,  it  is  plain,  that  with 
its  separation,  and  that  of  all  substances  capable  of 
attracting  oxygen,  the  beer  would  lose  the  property 
of  becoming  acid.  This  end  is  completely  attained 
in  the  process  of  fermentation  adopted  in  Bavaria. 

The  wort,  after  having  been  treated  with  hops  in 
the  usual  manner,  is  thrown  into  very  wide  flat 
vessels,  in  which  a  large  surface  of  the  liquid  is 
exposed  to  the  air.  The  fermentation  is  then  allowed 
to  proceed,  while  the  temperature  of  the  chambers 
in  which  the  vessels  are  placed  is  never  allowed  to 
rise  above  from  45  to  50^  F.  The  fermentation  lasts 
from    three    to    six   weeks,  and    the    carbonic    acid 


THE  BAVARIAN  PROCESS.  349 

evolved  during  its  continuance  is  not  in  large  bub- 
bles which  burst  upon  the  surface  of  the  liquid,  but 
in  small  bubbles  like  those  which  escape  from  a 
liquid  saturated  by  high  pressure.  The  surface  of 
the  wort  is  scarcely  covered  with  a  scum,  and  all 
the  yeast  is  deposited  on  the  bottom  of  the  vessel 
in  the  form  of  a  viscous  sediment. 

In  order  to  obtain  a  clear  conception  of  the  great 
difference  between  the  two  kinds  of  fermentation,  it 
may  perhaps  be  sufficient  to  recall  to  mind  the  fact, 
that  the  transformation  of  gluten  or  other  azotized 
matters  is  a  process  consisting  of  several  stages. 
The  first  stage  is  the  conversion  of  the  gluten  into 
insoluble  ferment  in  the  interior  of  the  liquid,  and 
as  the  transformation  of  the  sugar  goes  on  at  the 
same  time,  carbonic  acid  and  yeast  are  simultane- 
ously disengaged.  It  is  known  with  certainty,  that 
this  formation  of  yeast  depends  upon  oxygen  being 
appropriated  by  the  gluten  in  the  act  of  decomposi- 
tion ;  but  it  has  not  been  sufficiently  shown,  whether 
this  oxygen  is  derived  from  the  water,  sugar,  or- 
from  the  gluten  itself;  whether  it  combines  directly 
with  the  gluten,  or  merely  with  its  hydrogen,  so  as 
to  form  water.  For  the  purpose  of  obtaining  a 
definite  idea  of  the  process,  we  may  designate  the* 
first  change  as  the  stage  of  oxidation.  This  oxida- 
tion of  the  gluten,  then,  and  the  transposition  of  the 
atoms  of  the  sugar  into  alcohol  and  carbonic  acid, 
are  necessarily  attendant  on  each  other,  so  that  if  the 
one  is  arrested  the  other  must  also  cease. 

Now,  the  yeast  which  rises  to  the  surface  of  the 
liquid  is  not  the  product  of  a  complete  decomposi- 
tion, but  is  oxidized  gluten,  still  capable  of  under- 
going a  new  transformation  by  the  transposition  of 
its  constituent  elements.  By  virtue  of  this  condition 
it  has  the  power  to  excite  fermentation  in  a  solution 
of  sugar ;  and  if  the  gluten  be  also  present,  the 
decomposing  sugar  induces  its  conversion  into  fresh 
yeast,  so  that,  in  a  certain  sense,  the  yeast  appears: 
to  reproduce  itself. 

30 


350  FERMENTATION  OF  BEER. 

Yeast  of  this  kind  is  oxidized  gluten  in  a  state  of 
putrefaction,  and  by  virtue  of  this  state  it  induces 
a  similar  transformation  in  the  elements  of  the  sup-ar. 

The  yeast  formed  during  the  fermentation  of  Ba- 
varian beer  is  oxidized  gluten  in  a  state  of  decay. 
The  process  of  decomposition  which  its  constituents 
are  suffering,  gives  rise  to  a  very  protracted  putre- 
faction {^fei^mentation)  in  the  sugar.  The  intensity 
of  the  action  is  diminished  in  so  great  a  degree, 
that  the  gluten  which  the  fluid  still  holds  in  solution 
takes  no  part  in  it ;  the  sugar  in  fermentation  does 
not  excite  a  similar  state  in  the  gluten. 

But  the  contact  of  the  already  decaying  and  pre- 
cipitated gluten  or  yeast,  causes  the  eremacausis  of 
the  gluten  dissolved  in  the  wort ;  oxygen  gas  is 
absorbed  from  the  air,  and  all  the  gluten  in  solution 
is  deposited  as  yeast. 

The  ordinary  frothy  yeast  may  be  removed  from 
fermenting  beer  by  filtration,  without  the  fermenta- 
tion being  thereby  arrested ;  but  precipitated  yeast 
of  Bavarian  beer  cannot  be  removed  without  the 
whole  process  of  its  fermentation  being  interrupted. 
The  beer  ceases  to  ferment  altogether,  or,  if  the 
temperature  is  raised,  undergoes  the  ordinary  fer- 
mentation. 

The  precipitated  yeast  does  not  excite  ordinary 
fermentation,  and  consequently  is  quite  unfitted  for 
the  purpose  of  baking ;  but  the  common  frothy  yeast 
can  cause  the  kind  of  fermentation  by  which  the 
former  kind  of  yeast  is  produced. 

When  common  yeast  is  added  to  wort  at  a  tem- 
perature of  between  40^  and  45°  F.,  a  slow  tranquil 
fermentation  takes  place,  and  a  matter  is  deposited 
on  the  bottom  of  the  vessel,  which  may  be  employed 
to  excite  new  fermentation ;  and  when  the  same 
operation  is  repeated  several  times  in  succession, 
the  ordinary  fermentation  changes  into  that  process 
by  which  only  precipitated  yeast  is  formed.  The 
yeast  now  deposited  has  lost  the  property  of  excit- 


THE  BAVARIAN  PROCESS.  351 

ing  ordinary  fermentation,  but  it  produces  the  other 
process  even  at  a  temperature  of  50^  F. 

In  wort  subjected  to  fermentation,  at  a  low  tem- 
perature, with  this  kind  of  yeast,  the  condition 
necessary  for  the  transformation  of  the  sugar  is  the 
presence  of  that  yeast;  but  for  the  conversion  of 
gluten  into  ferment  by  a  process  of  oxidation,  some- 
thing more  is  required. 

When  the  power  of  gluten  to  attract  oxygen  is 
increased  by  contact  with  precipitated  yeast  in  a 
state  of  decay,  the  unrestrained  access  of  air  is  the 
only  other  condition  necessary  for  its  own  conver- 
sion into  the  same  state  of  decay,  that  is,  for  its 
oxidation.  We  have  already  seen,  that  the  presence 
of  free  oxygen  and  gluten  are  conditions  which 
determine  the  eremacausis  of  alcohol  and  its  conver- 
sion into  acetic  acid,  but  they  are  incapable  of  exert- 
ing this  influence  at  low  temperatures.  A  low  tem- 
perature retards  the  slow  combustion  of  alcohol, 
while  the  gluten  combines  spontaneously  with  the 
oxygen  of  the  air,  just  as  sulphurous  acid  does  when 
dissolved  in  water.  Alcohol  undergoes  no  such 
change  at  low  temperatures,  but  during  the  oxidation 
of  the  gluten  in  contact  with  it,  is  placed  in  the  same 
condition  as  the  gluten  itself  when  sulphurous  acid 
is  added  to  the  wine  in  which  it  is  contained.  The 
oxygen  of  the  air  unites  both  with  the  gluten  and 
alcohol  of  wine  not  treated  with  sulphurous  acid ; 
but  when  this  acid  is  present  it  combines  with  nei- 
ther of  them,  being  altogether  absorbed  by  the  acid. 
The  same  thing  happens  in  the  peculiar  process  of 
fermentation  adopted  in  Bavaria.  The  oxygen  of 
the  air  unites  only  with  the  gluten  and  not  with  the 
alcohol,  although  it  would  have  combined  with  both 
at  higher  temperatures,  so  as  to  form  acetic  acid. 

Thus,  then,  this  remarkable  process  of  fermenta- 
tion with  the  precipitation  of  a  mucous-like  ferment 
consists  of  a  simultaneous  putrefaction  and  decay  in 
the  same  liquid.  The  sugar  is  in  the  state  of  putre- 
faction, and  the  gluten  in  that  of  decay. 


352  FERMENTATION  OF  BEER. 

Appert's  method  of  preserving  food,  and  this  kind 
of  fermentation  of  beer,  depend  on  the  same  prin- 
ciple. 

In  the  fermentation  of  beer  after  this  manner,  all 
the  substances  capable  of  decay  are  separated  from 
it  by  means  of  an  unrestrained  access  of  air,  while 
the  temperature  is  kept  sufficiently  low  to  prevent 
the  alcohol  from  combining  with  oxygen.  The  re- 
moval of  these  substances  diminishes  the  tendency 
of  the  beer  to  become  acescent,  or,  in  other  words, 
to  suffer  a  further  transformation. 

In  Appert's  mode  of  preserving  food,  oxygen  is 
allowed  to  enter  into  combination  with  the  substance 
of  the  food,  at  a  temperature  at  which  decay,  but 
neither  putrefaction  nor  fermentation,  can  take  place. 
With  the  subsequent  exclusion  of  the  oxygen  and 
the  tiompletion  of  the  decay,  every  cause  which  could 
effect  further  decomposition  of  the  food  is  removed. 
The  conditions  for  putrefaction  are  rendered  insuffi- 
cient in  both  cases  ;  in  the  one  by  the  removal  of  the 
substances  susceptible  of  decay,  in  the  other  by  the 
exclusion  of  the  oxygen  which  would  effect  it. 

It  has  been  stated  to  be  uncertain,  whether  gluten 
during  its  conversion  into  common  yeast,  that  is, 
into  the  insoluble  state  in  which  it  separates  from 
fermenting  liquids,  really  combines  directly  with 
oxygen.  If  it  does  combine  with  oxygen,  then  the 
difference  between  gluten  and  ferment  would  be, 
that  the  latter  would  contain  a  larger  proportion  of 
oxygen.  Now  it  is  very  difficult  to  ascertain  this, 
and  even  their  analyses  cannot  decide  the  question. 
Let  us  consider,  for  example,  the  relations  of  alloxan 
and  alloxantin*  to  one  another.  Both  of  these  bod- 
ies contain  the  same  elements  as  gluten,  although  in 
different  proportions.  Now  they  are  known  to  be 
convertible  into  each  other,  by  oxygen  being  absorb- 
ed in  the  one  case,  and  in  the  other  extracted.    Both 

*  Products  of  the  decomposition  of  uric  acid  by  nitric  acid,  consisting' 
of  carbon,  nitrogen,  hydrogen,  and  oxygen.  See  description,  &c.  in 
Webster's  Chemistry^  pp.  425  and  430. 


FERMENTATION  OF  BEER.  353 

are  composed  of  absolutely  the  same  elements,  in 
equal  proportions  ;  with  the  single  exception,  that 
alloxantin  contains  1  equivalent  of  hydrogen  more 
than  alloxan. 

When  alloxantin  is  treated  with  chlorine  and  ni- 
tric acid,  it  is  converted  into  alloxan,  into  a  body, 
therefore,  which  is  alloxantin  minus  1  equivalent  of 
hydrogen.  If  on  the  other  hand  a  stream  of  sulphuret- 
ted hydrogen  is  conducted  through  alloxan,  sulphur 
is  precipitated,  and  alloxantin  produced.  It  may  be 
said,  that  in  the  first  case  hydrogen  is  abstracted, 
in  the  other  added.  But  it  would  be  quite  as  simple 
an  explanation,  if  we  considered  them  as  oxides  of 
the  same  radical :  the  alloxan  being  regarded  as  a 
combination  of  a  body  composed  of  C^  N^  ff  0^  with 
2  equivalents  of  water,  and  alloxantin  as  a  combina- 
tion of  3  atoms  of  water,  with  a  compound  consist- 
ing of  C^  N^  W  0^.  The  conversion  of  alloxan  into 
alloxantin  would  in  this  case  result  from  its  eight 
atoms  of  oxygen  being  reduced  to  seven,  while  al- 
loxan would  be  formed  out  of  alloxantin,  by  its  com- 
bining with  an  additional  atom  of  oxygen. 

Now,  oxides  are  known  which  combine  with  water, 
and  present  the  same  phenomena  as  alloxan  and  al- 
loxantin. But  no  compounds  of  hydrogen  are  known 
which  form  hydrates ;  and  custom,  which  rejects  all 
dissimilarity  until  the  claim  to  peculiarity  is  quite 
proved,  leads  us  to  prefer  an  opinion,  for  which  there 
is  no  further  foundation  than  that  of  analogy.  The 
woad  [Isatis  tinctoria)  and  several  species  of  the 
Nerium  contain  a  substance  similar  in  many  respects 
to  gluten,  which  is  deposited  as  indigo  blue,  when 
an  aqueous  infusion  of  the  dried  leaves  is  exposed 
to  the  action  of  the  air.  Now  it  is  very  doubtful 
whether  the  blue  insoluble  indigo  is  an  oxide  of  the 
colorless  soluble  indigo,  or  the  latter  a  combination 
of  hydrogen  with  the  indigo  blue.  Dumas  has  found 
the  same  elements  in  both,  except  that  the  soluble 
compound  contained  1  equivalent  of  hydrogen  more 
than  the  blue. 

30* 


354  FERMENTATION  OF  BEER. 

In  the  same  manner  the  soluble  gluten  may  be  con- 
sidered a  compound  of  hydrogen,  which  becomes 
ferment  by  losing  a  certain  quantity  of  this  element 
when  exposed  to  the  action  of  the  oxygen  of  the  air 
under  favorable  circumstances.  At  all  events,  it  is 
certain  that  oxygen  is  the  cause  of  the  insoluble  con- 
dition of  gluten ;  for  yeast  is  not  deposited  on  keep- 
ing wine,  or  during  the  fermentation  of  Bavarian 
beer,  unless  oxygen  has  access  to  the  fluid. 

Now,  whatever  be  the  form  in  which  the  oxygen 
unites  with  the  gluten,  —  whether  it  combines  di- 
rectly with  it  or  extracts  a  portion  of  its  hydrogen, 
forming  water,  —  the  products  formed  in  the  interior 
of  the  liquid,  in  consequence  of  the  conversion  of 
the  gluten  into  ferment,  will  still  be  the  same.  Let 
us  suppose  that  gluten  is  a  compound  of  another 
substance  with  hydrogen,  then  this  hydrogen  must 
be  removed  during  the  ordinary  fermentation  of  must 
and  wort,  by  combining  with  oxygen,  exactly  as  in 
the  conversion  of  alcohol  into  aldehyde  *  by  erema- 
causis. 

In  both  cases  the  atmosphere  is  excluded;  the 
oxygen  cannot,  then,  be  derived  from  the  air,  neither 
can  it  be  supplied  by  the  elements  of  water,  for  it  is 
impossible  to  suppose,  that  the  oxygen  will  separate 
from  the  hydrogen  of  water,  for  the  purpose  of  unit- 
ing with  the  hydrogen  of  gluten,  in  order  again  to 
form  water.  The  oxygen,  must,  therefore,  be  ob- 
tained from  the  elements  of  sugar,  a  portion  of  which 
substance  must,  in  order  to  the  formation  of  ferment, 
undergo  a  different  decomposition  from  that  which 
produces  alcohol.  Hence  a  certain  part  of  the  sugar 
will  not  be  converted  into  carbonic  acid  and  alcohol, 
but  will  yield  other  products  containing  less  oxygen 
than  sugar  itself  contains.  These  products,  as  has 
already  been  mentioned,  are  the  cause  of  the  great 

*  A  liquid  having  a  peculiar  ethereal  smell,  and  obtained  by  passing 
the  vapor  of  ether  through  a  large  glass  tube  heated  to  redness,  and  by 
other  processes.  It  consists  of  carbon  4 ,  hydrogen  4,  oxygen  2.  Its 
name  is  from  the  Latin,  alcohol  dehydratus. 


THE  BAVARIAN  PROCESS.  355 

difference  in  the  qualities  of  fermented  liquids,  and 
particularly  in  the  quantity  of  alcohol  which  they 
contain. 

Must  and  wort  do  not,  therefore,  in  ordinary  fer- 
mentation, yield  alcohol  in  proportion  to  the  quantity 
of  sugar  which  they  hold  in  solution,  a  part  of  the 
sugar  being  employed  in  the  conversion  of  gluten 
into  ferment,  and  not  in  the  formation  of  alcohol. 
But  in  the  fermentation  of  Bavarian  beer,  all  the 
sugar  is  expended  in  the  production  of  alcohol ;  and 
this  is  especially  the  case  whenever  the  transforma- 
tion of  the  sugar  is  not  accompanied  by  the  forma- 
tion of  yeast. 

It  is  quite  certain,  that  in  the  distilleries  of  brandy 
from  potatoes,  where  no  yeast  is  formed,  or  only  a 
quantity  corresponding  to  the  malt  which  has  been 
added,  the  proportion  of  alcohol  and  carbonic  acid 
obtained  during  the  fermentation  of  the  mash  corre- 
sponds exactly  to  that  of  the  carbon  contained  in 
the  starch.  It  is  also  known,  that  the  volume  of  car- 
bonic acid  evolved  during  the  fermentation  of  beet- 
roots gives  no  exact  indication  of  the  proportion  of 
sugar  contained  in  them,  for  less  carbonic  acid  is 
obtained  than  the  same  quantity  of  pure  sugar  would 
yield. 

Beer  obtained  by  the  mode  of  fermentation  adopt- 
ed in  Bavaria  contains  more  alcohol,  and  possesses 
more  intoxicating  properties,  than  that  made  by  the 
ordinary  method  of  fermentation,  when  the  quanti- 
ties of  malt  used  are  the  same.  The  strong  taste 
of  the  former  beer  is  generally  ascribed  to  its  con- 
taining carbonic  acid  in  larger  quantity,  and  in  a 
state  of  more  intimate  combination ;  but  this  opinion 
is  erroneous.  Both  kinds  of  beer  are,  at  the  conclu- 
sion of  the  fermentation,  completely  saturated  with 
carbonic  acid,  the  one  as  much  as  the  other.  Like 
all  other  liquids,  they  both  must  retain  such  a  por- 
tion of  the  carbonic  acid  evolved  as  corresponds  to 
their  power  of  solution,  that  is,  to  their  volumes. 

The  temperature  of  the  fluid  during  fermentation 


356  FERMENTATION  OF  BEER. 

has  a  very  important  influence  on  the  quantity  of 
alcohol  generated.  It  has  been  mentioned,  that  the 
juice  of  beet-roots  allowed  to  ferment  at  from  86^  to 
950  (30^  to  350  C.)  yields  no  alcohol;  and  that 
afterwards,  in  the  place  of  the  sugar,  mannite,  a 
substance  incapable  of  fermentation,  and  containing 
very  little  oxygen,  is  found,  together  with  lactic  acid 
and  mucilage.  The  formation  of  these  products  di- 
minishes in  proportion  as  the  temperature  is  lower. 
But  in  vegetable  juices,  containing  nitrogen,  it  is 
impossible  to  fix  a  limit,  where  the  transformation 
of  the  sugar  is  undisturbed  by  any  other  process  of 
decomposition. 

It  is  known,  that  in  the  fermentation  of  Bavarian 
beer,  the  action  of  the  oxygen  of  the  air,  and  the 
low  temperature,  cause  complete  transformation  of 
the  sugar  into  alcohol ;  the  cause  which  would  pre- 
vent that  result,  namely,  the  extraction  of  the  oxy- 
gen of  part  of  the  sugar  by  the  gluten,  in  its  con- 
version into  ferment,  being  avoided  by  the  introduc- 
tion of  oxygen  from  without. 

The  quantity  of  matters  in  the  act  of  transforma- 
tion is  naturally  greatest  at  the  beginning  of  the 
fermentation  of  must  and  wort ;  and  all  the  phenom- 
ena which  accompany  the  process,  such  as  evolution 
of  gas,  and  heat,  are  best  observed  at  that  time. 
These  signs  of  the  changes  proceeding  in  the  fluid 
diminish  when  the  greater  part  of  the  sugar  has 
undergone  decomposition ;  but  they  must  cease  en- 
tirely before  the  process  can  be  regarded  as  com- 
pleted. 

The  less  rapid  process  of  decomposition  which 
succeeds  the  violent  evolution  of  gas,  continues  in 
wine  and  beer  until  the  sugar  has  completely  dis- 
appeared; and  hence  it  is  observed,  that  the  specific 
gravity  of  the  liquid  diminishes  during  many  months. 
This  slow  fermentation,  in  most  cases,  resembles  the 
fermentation  of  Bavarian  beer,  the  transformation 
of  the  dissolved  sugar  being  in  part  the  result  of  a 
slow  and  continued  decomposition  of  the  precipita- 


DECAY  OF  WOODY  FIBRE.  357 

ted  yeast ;  but  a  complete  separation  of  the  azotized 
substances  dissolved  in  it  cannot  take  place  when 
air  is  excluded.* 

Neither  alcohol  alone,  nor  hops,  nor  indeed  both 
together,  preserve  beer  from  becoming  acid.  The 
better  kinds  of  ale  and  porter  in  England  are  pro- 
tected from  acidity,  but  at  the  loss  of  the  interest 
of  an  immense  capital.  They  are  placed  in  large 
closed  wooden  vessels,  the  surfaces  of  which  are 
covered  with  sand.  In  these  they  are  allowed  to  lie 
for  several  years,  so  that  they  are  treated  in  a  man- 
ner exactly  similar  to  wine  during  its  ripening. 

A  gentle  diffusion  of  air  takes  place  through  the 
pores  of  the  wood,  but  the  quantity  of  azotized  sub- 
stances being  very  great  in  proportion  to  the  oxygen 
which  enters,  they  consume  it,  and  prevent  its  union 
with  the  alcohol.  But  the  beer  treated  in  this  way 
does  not  keep  for  two  months  without  acidifying  if 
it  be  placed  in  smaller  vessels,  to  which  free  access 
of  the  air  is  permitted. 


CHAPTER  X. 

DECAY  OF  Vi^OODY  FIBRE. 

The  conversion  of  woody  fibre  into  the  substances 
termed  humus  and  mould  is,  on  account  of  its  in- 
fluence on  vegetation,  one  of  the  most  remarkable 
processes  of  decomposition  which  occur  in  nature. 

Decay  is   not  less   important  in  another  point  of 

*  The  great  influence  which  a  rational  management  of  fermentation 
exercises  upon  the  quahty  of  beer  is  well  known  in  several  of  the  Ger- 
man states.  In  the  grand-duchy  of  Hesse,  for  example,  a  considerable 
premium  is  offered  for  the  preparation  of  beer,  according  to  the 
Bavarian  method;  and  the  premium  is  to  be  adjudged  to  any  one  who 
can  prove,  that  the  beer  brewed  by  him  has  lain  for  six  months  in  the 
store-vats  without  becoming  acid.  Hundreds  of  casks  of  beer  became 
changed  to  vinegar  before  an  empirical  knowledge  of  those  conditions 
was  obtained,  the  influence  of  which  is  rendered  intelligible  by  the 
theory.  —  L. 


358  DECAY  OF  WOODY  FIBRE. 

view ;  for,  by  means  of  its  influence  on  dead  vege- 
table matter,  the  oxygen  which  plants  retained  dur- 
ing life  is  again  restored  to  the  atmosphere. 

The  decomposition  of  w^oody  fibre  is  effected  in 
three  forms,  the  results  of  which  are  different,  so 
that  it  is  necessary  to  consider  each  separately. 

The  first  takes  place  when  it  is  in  the  moist  con- 
dition, and  subject  to  free  uninterrupted  access  of 
air ;  the  second  occurs  when  the  air  is  excluded ; 
and  the  third  when  the  wood  is  covered  with  water, 
and  in  contact  with  putrefying  organic  matter. 

It  is  known  that  woody  fibre  may  be  kept  under 
water,  or  in  dry  air,  for  thousands  of  years  without 
suffering  any  appreciable  change ;  but  that  when 
brought  into  contact  with  air,  in  the  moist  con- 
dition it  converts  the  oxygen  surrounding  it  into  the 
same  volume  of  carbonic  acid,  and  is  itself  gradually 
changed  into  a  yellowish  brown,  or  black  matter,  of 
a  loose  texture.* 

It  has  already  been  mentioned,  that  pure  woody 
fibre  contains  carbon  and  the  elements  of  water. 
Humus,  however,  is  not  produced  by  the  decay  of 
pure  woody  fibre,  but  by  that  of  wood  which  contains 
foreign  soluble  and  insoluble  organic  substances,  be- 
sides its  essential  constituents. 

The  relative  proportions  of  the  component  elements 
are,  on  this  account,  different  in  oak  wood  and  in 
beech,  and  the  composition  of  both  of  these  differs 
very  much  from  woody  fibre,  which  is  the  same  in 
all  vegetables.  The  difference,  however,  is  so  triv- 
ial, that  it  may  be  altogether  neglected  in  the  con- 
sideration of  the  questions  which  will  now  be  brought 
under  discussion ;  besides,  the  quantity  of  the  for- 
eign substances  is  not  constant,  Ijut  varies  according 
to  the  season  of  the  year. 

*  According  to  the  experiments  of  De  Saussure,  240  parts  of  dry 
saw-dust  of  oak  wood  convert  10  cubic  inches  of  oxygen  into  the  same 
quantity  of  carbonic  acid,  which  contains  3  parts,  by  weight,  of  car- 
bon ;  while  the  weight  of  the  sawdust  is  diminished  by  15  parts. 
Hence,  12  parts,  by  weight,  of  water,  are  at  the  same  time  separated 
from  the  elements  of  the  wood.  —  L. 


DECAY  OF  WOODY  FIBRE.  359 

According  to  the  careful  analysis  of  Gay-Lussac 
and  Thenard,  100  parts  of  oak  wood,  dried  at  212^ 
(100^  C),  from  which  all  soluble  substances  had 
been  extracted  by  means  of  water  and  alcohol,  con- 
tained 52-53  parts  of  carbon,  and  47*47  parts  of  hy- 
drogen and  oxygen,  in  the  same  proportion  as  they 
are  contained  in  water.  ' 

Now  it  has  been  mentioned,  that  moist  wood  acts 
in  oxygen  gas  exactly  as  if  its  carbon  combined  di- 
rectly with  oxygen,  and  that  the  products  of  this 
action  are  carbonic  acid  and  humus. 

If  the  action  of  the  oxygen  were  confined  to  the 
carbon  of  the  wood,  and  if  nothing  but  carbon  were 
removed  from  it,  the  remaining  elements  would  ne- 
cessarily be  found  in  the  humus,  unchanged  except 
in  the  particular  of  being  combined  with  less  carbon. 
The  final  result  of  the  action  would  therefore  be  a 
complete  disappearance  of  the  carbon,  whilst  noth- 
ing but  the  elements  of  water  would  remain. 

But  when  decaying  wood  is  subjected  to  exami- 
nation in  different  stages  of  its  decay,  the  remark- 
able result  is  obtained,  that  the  proportion  of  carbon 
in  the  different  products  augments.  Consequently, 
if  we  did  not  take  into  consideration  the  evolution 
of  carbonic  acid  under  the  influence  of  the  air,  the 
conversion  of  wood  into  humus  might  be  viewed  as 
a  removal  of  the  elements  of  water  from  the  carbon. 

The  analysis  of  mouldered  oak  wood,  which  was 
taken  from  the  interior  of  the  trunk  of  an  oak,  and 
possessed  a  chocolate  brown  color  and  the  structure 
of  wood,  showed  that  100  parts  of  it  contained  53*56 
parts  of  carbon  and  46*44  parts  of  hydrogen  and 
oxygen  in  the  same  relative  proportions  as  in  w^ater. 
From  an  examination  of  mouldered  wood  of  a  light- 
brown  color,  easily  reducible  to  a  fine  powder,  and 
taken  from  another  oak,  it  appeared  that  it  contained 
56-211  carbon  and  43*789  water. 

These  indisputable  facts  point  out  the  similarity 
of  the  decay  of  wood,  with  the  slow  combustion  or 
oxidation  of  bodies  which  contain  a  large  quantity 


360  DECAY  OF  WOODY  FIBRE. 

of  hydrogen.  Viewed  as  a  kind  of  combustion,  it 
would  indeed  be  a  very  extraordinary  process,  if  the 
carbon  combined  directly  wdth  the  oxygen;  for  it 
would  be  a  combustion  in  which  the  carbon  of  the 
burning  body  augmented  constantly,  instead  of 
diminishing.  Hence  it  is  evident,  that  it  is  the  hy- 
drogen which  is  oxidized  at  the  expense  of  the 
oxygen  of  the  air;  while  the  carbonic  acid  is  formed 
from  the  elements  of  the  wood.  Carbon  never  com- 
bines at  common  temperatures  with  oxygen,  so  as  to 
form  carbonic  acid. 

In  whatever  stage  of  decay  wood  may  be,  its  ele- 
ments *  must  always  be  capable  of  being  represented 
by  their  equivalent  numbers. 

The  following  formula  illustrates  this  fact  with 
great  clearness  : 

C36  H22  022 — oak  wood,  according  to  Gay-Lussac  and  Th^nard.* 
C  35  H20  O 20  —  humus  from  oak  wood  (Meyer). t 
C34  H18  018—  *'  "  (Dr.  Will)4 

It  is  evident  from  these  numbers,  that  for  every 
two  equivalents  of  hydrogen  which  are  oxidized, 
two  atoms  of  oxygen  and  one  of  carbon  are  set 
free. 

Under  ordinary  circumstances,  woody  fibre  requires 
a  very  long  time  for  its  decay;  but  this  process  is 
of  course  much  accelerated  by  an  elevated  tempera- 
ture and  free  unrestrained  access  of  air.  The  decay, 
on  the  contrary,  is  much  retarded  by  absence  of 
moisture,  and  by  the  wood  being  surrounded  w^ith 
an  atmosphere  of  carbonic  acid,  which  prevents  the 
access  of  air  to  the  decaying  matters. 

Sulphurous  acid,  and  all  antiseptic  substances, 
arrest  the  decay  of  woody  fibre.  It  is  well  known, 
that  corrosive  sublimate  is  employed  for  the  purpose 
of  protecting  the  timber  of  ships  from  decay ;  it  is 
a  substance  which  completely  deprives  vegetable  or 
animal  matters,  the  most  prone  to  decomposition,  of 

*  The  calculation  gives  52-5  carbon,  and  47-5  water, 
t  The  calculation  gives  54  carbon,  and  46  water. 
t  The  calculation  gives  56  carbon,  and  44  water. 


WOODY  FIBRE.  361 

their  property  of  entering  into  fermentation,  putre- 
faction, or  decay.* 

But  the  decay  of  woody  fibre  is  very  much  accel- 
erated by  contact  with  alkalies  or  alkaline  earths ; 
for  these  enable  substances  to  absorb  oxygen,  which 
do  not  possess  this  power  themselves ;  alcohol, 
gallic  acid,  tannin,  the  vegetable  coloring  matters, 
and  several  other  substances,  are  thus  affected  by 
them.  Acids  produce  quite  an  opposite  eflfect ;  they 
greatly  retard  decay. 

Heavy  soils,  consisting  of  loam,  retain  longest  the 
most  important  condition  for  the  decay  of  the  vege- 
table matter  contained  in  them,  viz.,  water;  but 
their  impermeable  nature  prevents  contact  with  the 
air. 

In  moist  sandy  soils,  particularly  such  as  are  com- 
posed of  a  mixture  of  sand  and  carbonate  of  lime, 
decay  proceeds  very  quickly,  it  being  aided  by  the 
presence  of  the  slightly  alkaline  lime. 

Now  let  us  consider  the  decay  of  woody  fibre 
during  a  very  long  period  of  time,  and  suppose  that 
its  cause  is  the  gradual  removal  of  the  hydrogen  in 
the  form  of  water,  and  the  separation  of  its  oxygen 
in  that  of  carbonic  acid.  It  is  evident,  that  if  we 
subtract  from  the  formula  C^%  W^,  0^^,  the  22  equiv- 
alents of  oxygen,  with  11  equivalents  of  carbon,  and 
22  equivalents  of  hydrogen,  which  are  supposed  to 
be  oxidized  by  the  oxygen  of  the  air,  and  separated 
in  the  form  of  water;  then  from  1  atom  of  oak  wood, 
25  atoms  of  pure  carbon  will  remain  as  the  final 
product  of  the  decay.  In  other  words,  100  parts  of 
oak,  which  contain  52*5  parts  of  carbon,  will  leave 
as  a  residue  37  parts  of  carbon,  which  must  remain 
unchanged,  since  carbon  does  not  combine  with 
oxygen  at  common  temperatures. 

But  this  final  result  is  never  attained  in  the  decay 
of  wood  under  common  circumstances ;  and  for  this 
reason,  that  with  the  increase  of  the  proportion  of 

*  See  an  account  of  the  process  for  *'  kyanizing"  timber  in  the  Farm- 
fir's  Register,  Vol.  III.  p.  368. 

31 


362  DECAY  OF  WOODY  FIBRE. 

carbon  in  the  residual  humus,  as  in  all  decomposi- 
tions of  this  kind,  its  attraction  for  the  hydrogen, 
which  still  remains  in  combination,  also  increases, 
until  at  length  the  affinity  of  oxygen  for  the  hydro- 
gen is  equalled  by  that  of  the  carbon  for  the  same 
element. 

In  proportion  as  the  decay  of  woody  fibre  ad- 
vances, its  property  of  burning  with  flame,  or  in 
other  words,  of  developing  carburetted  hydrogen  on 
the  application  of  heat,  diminishes.  Decayed  wood 
burns  without  flame ;  whence  no  other  conclusion 
can  be  drawn,  than  that  the  hydrogen,  which  analysis 
shows  to  be  present,  is  not  contained  in  it  in  the 
same  form  as  in  wood. 

Decayed  oak  contains  more  carbon  than  fresh 
wood,  but  its  hydrogen  and  oxygen  are  in  the  same 
proportion. 

We  should  naturally  expect  that  the  flame  given 
out  by  decayed  wood  would  be  more  brilliant,  in 
proportion  to  the  increase  of  its  carbon;  but  we  find, 
on  the  contrary,  that  it  burns  like  tinder,  exactly  as  if 
no  hydrogen  were  present.  For  the  purposes  of  fuel, 
decayed  or  diseased  wood  is  of  little  value,  for  it 
does  not  possess  the  property  of  burning  with  flame, 
a  property  upon  which  the  advantages  of  common 
wood  depend.  The  hydrogen  of  decayed  wood  must 
consequently  be  supposed  to  be  in  the  state  of  water; 
for  had  it  any  other  form,  the  characters  we  have  de- 
scribed would  not  be  possessed  by  the  decayed  wood. 

If  we  suppose  decay  to  proceed  in  a  liquid,  which 
contains  both  carbon  and  hydrogen,  then  a  compound 
containing  still  more  carbon  must  be  formed,  in  a 
manner  similar  to  the  production  of  the  crystalline 
colorless  naphthalin  from  a  gaseous  compound  of 
carbon  and  hydrogen.  And  if  the  compound  thus 
formed  were  itself  to  undergo  further  decay,  the 
final  result  must  be  the  separation  of  carbon  in  a 
crystalline  form. 

Science  can  point  to  no  process  capable  of  ac- 
counting for  the  origin  and  formation  of  diamonds, 


VEGETABLE  MOULD.  363 

except  the  process  of  decay.  Diamonds  cannot  be 
produced  by  the  action  of  fire,  for  a  high  temperature 
and  the  presence  of  oxygen  gas,  would  call  into 
play  their  combustibility.  But  there  is  the  greatest 
reason  to  believe  that  they  are  formed  in  the  humid 
way,  that  is,  in  a  liquid,  and  the  process  of  decay  is 
the  only  cause  to  which  their  formation  can  with 
probability  be  ascribed. 

Amber,  fossil  resin,  and  the  acids  in  mellite,  are 
the  products  of  vegetable  matter  which  has  suffered 
decomposition.  They  are  found  in  wood  or  brown 
coal,  and  have  evidently  proceeded  from  the  decom- 
position of  substances  which  were  contained  in  quite 
a  different  form  in  the  living  plants.  They  are  all 
distinguished  by  the  proportionally  small  quantity 
of  hydrogen  which  they  contain.  The  acid  from 
mellite  (mellitic  acid)  contains  precisely  the  same 
proportions  of  carbon  and  oxygen  as  that  from 
amber  (succinic  acid);  they  differ  only  in  the  pro- 
portion of  their  hydrogen.  M.  Bromeis*  found,  that 
succinic  acid  might  be  artificially  formed  by  the 
action  of  nitric  acid  on  stearic  acid,  a  true  process 
of  eremacausis ;  the  experiment  was  made  in  this 
laboratory  (Giessen). 


CHAPTER  XL 

VEGETABLE  MOULD. 

The  term  vegetable  mouldy  in  its  general  significa- 
tion, is  applied  to  a  mixture  of  disintegrated  miner- 
als, with  the  remains  of  animal  and  vegetable  sub- 
stances. It  may  be  considered  as  earth  in  which 
humus  is  contained  in  a  state  of  decomposition.  Its 
action  upon  the  air  has  been  fully  investigated  by 
Ingenhouss  and  De  Saussure. 

When  moist  vegetable  mould  is  placed  in  a  vessel 

^^■^^        ■    II  ■■—■■■■■        ,  I  ■■^—  I   -I  ■—■■■■■       I   ■       .^i.i  ■  ■  ■■■    ■         ^ .  _■    .11      .  ^— ^^i^p^^ 

*  Liebig's  Annalen,  Band  xxxiv.,  heft  3. 


364  VEGETABLE  MOULD. 

full  of  air,  it  extracts  the  oxygen  therefrom  with 
greater  rapidity  than  decayed  wood,  and  replaces  it 
by  an  equal  volume  of  carbonic  acid.  When  this 
carbonic  acid  is  removed  and  fresh  air  admitted, 
the  same  action  is  repeated. 

Cold  water  dissolves  only  icoogth  of  its  own  weight 
of  vegetable  mould ;  and  the  residue  left  on  its 
evaporation  consists  of  common  salt  with  traces  of 
sulphate  of  potash  and  lime,  and  a  minute  quantity 
of  organic  matter,  for  it  is  blackened  when  heated 
to  redness.  Boiling  water  extracts  several  sub- 
stances from  vegetable  mould,  and  acquires  a  yellow 
or  yellowish  brown  color,  which  is  dissipated  by 
absorption  of  oxygen  from  the  air,  a  black  flocculent 
deposit  being  formed.  When  the  colored  solution  is 
evaporated,  a  residue  is  left  which  becomes  black  on 
being  heated  to  redness,  and  afterwards  yields  car- 
bonate of  potash  when  treated  with  water. 

A  solution  of  caustic  potash  becomes  black  when 
placed  in  contact  with  vegetable  mould,  and  the  ad- 
dition of  acetic  acid  to  the  colored  solution  causes  no 
precipitate  or  turbidness.  But  dilute  sulphuric  acid 
throws  down  a  light  flocculent  precipitate  of  a  brown 
or  black  color,  from  which  the  acid  can  be  removed 
with  difficulty  by  means  of  water.  When  this  pre- 
cipitate, after  having  been  washed  with  water,  is 
brought  whilst  still  moist  under  a  receiver  filled  with 
oxygen,  the  gas  is  absorbed  with  great  rapidity;  and 
the  same  thing  takes  place  when  the  precipitate  is 
dried  in  the  air.  In  the  perfectly  dry  state  it  has 
entirely  lost  its  solubility  in  water,  and  even  alkalies 
dissolve  only  traces  of  it. 

It  is  evident,  therefore,  that  boiling  water  extracts 
a  matter  from  vegetable  mould,  which  owes  its  solu- 
bility to  the  presence  of  the  alkaline  salts  contained 
in  the  remains  of  plants.  This  substance  is  a  pro- 
duct of  the  incomplete  decay  of  woody  fibre.  Its 
composition  is  intermediate  between  woody  fibre  and 
humus,  into  which  it  is  converted,  by  being  exposed 
in  a  moist  condition  to  the  action  of  the  air. 


DECOMPOSITION  OF   WOOD,   COAL,  ETC.  365 


CHAPTER  XIL 

ON  THE  MOULDERING  OF   BODIES.  — PAPER,  BROWN 
COAL,  AND  MINERAL  COAL. 

The  decomposition  of  wood,  woody  fibre,  and  all 
vegetable  bodies  when  subjected  to  the  action  of 
water,  and  excluded  from  the  air,  is  termed  mould- 
ering. 

Wood,  or  brown  coal  and  mineral  coal,  are  the  re- 
mains of  vegetables  of  a  former  world;  their  ap- 
pearance and  characters  show,  that  they  are  products 
of  the  processes  of  decomposition  termed  decay  and 
putrefaction.  We  can  easily  ascertain  by  analysis 
the  manner  in  which  their  constituents  have  been 
changed,  if  we  suppose  the  greater  part  of  their  bulk 
to  have  been  formed  from  woody  fibre. 

But  it  is  necessary,  before  we  can  obtain  a  distinct 
idea  of  the  manner  in  which  coal  is  formed,  to  con- 
sider a  peculiar  change  which  woody  fibre  suffers  by 
means  of  moisture,  when  partially  or  entirely  ex- 
cluded from  the  air. 

It  is  known,  that  when  pure  woody  fibre,  as  linen, 
for  example,  is  placed  in  contact  w^ith  water,  con- 
siderable heat  is  evolved,  and  the  substance  is 
converted  into  a  soft  friable  mass,  which  has  lost 
all  coherence.  This  substance  was  employed  in  the 
fabrication  of  paper  before  the  use  of  chlorine,  as  an 
agent  for  bleaching.  The  rags  employed  for  this 
purpose  were  placed  in  heaps,  and  it  was  observed, 
that  on  their  becoming  warm  a  gas  was  disengaged, 
and  their  weight  diminished  from  18  to  25  per  cent. 

When  sawdust  moistened  with  water  is  placed  in 
a  closed  vessel,  carbonic  acid  gas  is  evolved  in  the 
same  manner  as  when  air  is  admitted.  A  true  putre- 
faction takes  place,  the  wood  assumes  a  white  color, 
loses  its  peculiar  texture,  and  is  converted  into  a 
rotten  friable  matter. 
31* 


366  DECOMPOSITION  OF  WOOD,  COAL,  ETC. 

The  white  decayed  wood  found  in  the  interiors  of 
trunks  of  dead  trees  which  have  been  in  contact  with 
water,  is  produced  in  the  way  just  mentioned. 

An  analysis  of  wood  of  this  kind,  obtained  from 
the  interior  of  the  trunk  of  an  oak,  yielded,  after 
having  been  dried  at  212^, 

.  48-14 
606 

.  44-43 
1-37 


Carbon 

48-11 

Hydrogen 

6-31 

Oxygen 
Ashes 

45-31 

1-27 

100-00  100-00 

Now,  on  comparing  the  proportions  obtained  from 
these  numbers  with  the  composition  of  oak  wood,  ac- 
cording to  the  analysis  of  Gay-Lussac  and  Thenard, 
it  is  immediately  perceived,  that  a  certain  quantity 
of  carbon  has  been  separated  from  the  constituents 
of  wood,  whilst  the  hydrogen  is,  on  the  contrary,  in- 
creased. The  numbers  obtained  by  the  analysis  cor- 
respond very  nearly  to  the  formula  C33  H27  024.* 

The  elements  of  water  have,  therefore,  become 
united  with  the  wood,  whilst  carbonic  acid  is  disen- 
gaged by  the  absorption  of  a  certain  quantity  of 
oxygen. 

If  the  elements  of  5  atoms  of  water  and  3  atoms 
of  oxygen  be  added  to  the  composition  of  the  woody 
fibre  of  the  oak,  and  3  atoms  of  carbonic  acid  de- 
ducted, the  exact  formula  for  white  mouldered  wood 
is  obtained. 

Wood C36H22  022 

To  this  add  5  atoms  of  water    .  .  H  5  O  5 

3  atoms  of  oxygen  ...  O  3 


C36  H27  O  30 
Subtract  from  this  3  atoms  carbonic  acid      C  3  O  6 


C33  H27  024 

The  process  of  mouldering  is,  therefore,  one  of 
putrefaction  and  decay,  proceeding  simultaneously, 
in  which  the   oxygen  of  the  air  and  the  component 


*  The  calculation  from  this  formula  gives  in  100  parts  47-9  carbon, 
6-1  hydrogen,  and  46  oxygen. 


DECOAIPOSITION  OF  WOOD,  COAL,  ETC.  367 

parts  of  water  take  part.  But  the  composition  of 
mouldered  wood  must  change  according  as  the 
access  of  oxygen  is  more  or  less  prevented.  White 
mouldered  beech-wood  yielded  on  analysis  47*67 
carbon,  5*67  hydrogen,  and  46*68  oxygen ;  this  cor- 
responds to  the  formula  C33  H25  024. 

The  decomposition  of  wood  assumes,  therefore, 
two  different  forms,  according  as  the  access  of  the 
air  is  free  or  restrained.  In  both  cases  carbonic 
acid  is  generated ;  and  in  the  latter  case,  a  certain 
quantity  of  water  enters  into  chemical  combination. 

It  is  highly  probable,  that  in  this  putrefactive 
process,  as  well  as  in  all  others,  the  oxygen  of  the 
water  assists  in  the  formation  of  the  carbonic  acid. 

Wood  coal  (brown  coal  of  Werner)  must  have 
been  produced  by  a  process  of  decomposition  similar 
to  that  of  mouldering.  But  it  is  not  easy  to  obtain 
wood  coal  suited  for  analysis,  for  it  is  generally 
impregnated  with  resinous  or  earthy  substances,  by 
which  the  composition  of  those  parts  which  have 
been  formed  from  woody  fibre  is  essentially  changed. 

The  wood  coal,  w^hich  forms   extensive   layers  in 

the  Wetterau  (a  district  in  Hesse    Darmstadt),  is 

distinguished  from  that  found   in   other   places,  by 

possessing  the  structure  of  wood  unchanged,  and  by 

containing  no   bituminous   matter.      This    coal  was 

subjected  to  analysis,  a  piece  being   selected   upon 

which  the  annual  circles  could  be  counted.     It  was 

obtained  from  the  vicinity  of  Laubach ;    100  parts 

contained 

Carbon  ...  57'28 

Hydrogen  ,            .            .  6*03 

Oxygen  ,            .            •  36*10 

Ashes  ....  0*59 


100-00 


The  large  amount  of  carbon,  and  small  quantity 
of  oxygen,  constitute  the  most  obvious  difference 
between  this  analysis  and  that  of  wood.  It  is  evi- 
dent, that  the  wood  which  has  undergone  the  change 
into  coal  must  have  parted  with  a  certain  portion  of 


368  DECOMPOSITION  OF  WOOD,  COAL,  ETC. 

its    oxygen.      The  proportion  of  these    numbers  is 
expressed  by  the  formula  C33  H21  016.* 

When  these  numbers  are  compared  with  those 
obtained  by  the  analysis  of  oak,  it  would  appear 
that  the  brown  coal  was  produced  from  woody  fibre 
by  the  separation  of  one  equivalent  of  hydrogen, 
and  the  elements  of  three  equivalents  of  carbonic 
acid. 

1  atom  wood        , C36  H22  022 

Minus  1  atom  hydrogen  and  3  atoms  car-  ^  r;  q  h  i  o  6 
bonic  acid S 


Wood  Coal   .    .    C33  H21  016 

All  varieties  of  wood  coal,  from  whatever  strata 
they  may  be  taken,  contain  more  hydrogen  than 
wood  does,  and  less  oxygen  than  is  necessary  to 
form  water  with  this  hydrogen ;  consequently,  they 
must  all  be  produced  by  the  same  process  of  decom- 
position. The  excess  of  hydrogen  is  either  hydro- 
gen of  the  wood  which  has  remained  in  it  unchanged, 
or  it  is  derived  from  some  exterior  source.  The 
analysis  of  wood  coal  from  Ringkuhl,  near  Cassel, 
where  it  is  seldom  found  in  pieces  with  the  structure 
of  wood,  gave,  when  dried  at  212^, 

Carbon 
Hydrogen 
Oxygen 
Ashes 

100-00  100-00 

The  proportions  derived  from  these  numbers  cor- 
respond very  closely  to  the  formula  C^^  H^^  0%  or 
they  represent  the  constituents  of  wood,  from  which 
the  elements  of  carbonic  acid,  water,  and  2  equiva- 
lents hydrogen,  have  been  separated. 

C36H22  022=Wood. 
Subtract  C  4  H  7  013  =  4  atoms  carbonic  acid  -}-5  atoms  of  water 

-j"  2  atoms  of  hydrogen. 

C32  H15  O  9  =  Wood  coal  from  Ringkuhl. 

The  formation  of  both  these  specimens  of  wood 
*  The  calculation  gives  57-5  carbon,  and  5-98  hydrogen. 


62-60 

6383 

502 

.      4-80 

26-52 

25-51 

5-86 

.      5-86 

FORMATION  OF  WOOD  COAL.  369 

coal  appears  from  these  formulae  to  have  taken  place 
under  circumstances  which  did  not  entirely  exclude 
the  action  of  the  air,  and  consequent  oxidation  and 
removal  of  a  certain  quantity  of  hydrogen.  Now 
the  Laubacher  coal  is  covered  with  a  layer  of  basalt, 
and  the  coal  of  Ringkuhl  was  taken  from  the  lowest 
seam  of  layers,  which  possess  a  thickness  of  from 
90  to  120  feet ;  so  that  both  may  be  considered  as 
well  protected  from  the  air. 

During  the  formation  of  brown  coal,  the  elements 
of  carbonic  acid  have  been  separated  from  the  wood 
either  alone,  or  at  the  same  time  with  a  certain  quan- 
tity of  water.  It  is  quite  possible,  that  the  difference 
in  the  process  of  decomposition  may  depend  upon 
the  high  temperature  and  pressure  under  which  the 
decomposition  took  place.  At  least,  a  piece  of  wood 
assumed  the  character  and  appearance  of  Laubacher 
coal,  after  being  kept  for  several  weeks  in  the  boiler 
of  a  steam-engine,  and  had  then  precisely  the  same 
composition.  The  change  in  this  case  was  effected  in 
water,  at  a  temperature  of  from  334°  to  352°  F. 
(150°— 160°  C),  and  under  a  corresponding  pres- 
sure. The  ashes  of  the  wood  amounted  to  0*51  per 
cent. ;  a  little  less,  therefore,  than  those  of  the  Lau- 
bacher coal ;  but  this  must  be  ascribed  to  the  pecu- 
liar circumstances  under  which  it  was  formed.  The 
ashes  of  plants  examined  by  Berthier  amounted 
always  to  much  more  than  this. 

The  peculiar  process  by  which  the  decomposition 
of  these  extinct  vegetables  has  been  effected,  namely, 
a  disengagement  of  carbonic  acid  from  their  sub- 
stance, appears  still  to  go  on  at  great  depths  in  all 
the  layers  of  wood  coal.  At  all  events  it  is  remark- 
able, that  springs  impregnated  with  carbonic  acid 
occur  in  many  places,  in  the  country  between  Meiss- 
ner,  in  the  electorate  of  Hesse,  and  the  Eifel,  which 
are  known  to  possess  large  layers  of  wood  coal. 
These  springs  of  mineral  water  are  produced  on  the 
spot  at  which  they  are  found ;  the  springs  of  com- 


370  CONVERSION  OF  WOOD 

mon  water  meeting  with  carbonic  acid  during  their 
ascent,  and  becoming  impregnated  with  it. 

In  the  vicinity  of  the  layers  of  wood  coal  at  Salz- 
hausen  (Hesse  Darmstadt)  an  excellent  acidulous 
spring  of  this  kind  existed  a  few  years  ago,  and 
supplied  all  the  inhabitants  of  that  district ;  but  it 
was  considered  advantageous  to  surround  the  sides 
of  the  spring  with  sandstone,  and  the  consequence 
was,  that  all  the  outlets  to  the  carbonic  acid  were 
closed,  for  this  gas  generally  gains  access  to  the 
water  from  the  sides  of  the  spring.  From  that  time 
to  the  present  this  valuable  mineral  water  has  dis- 
appeared, and  in  its  place  is  found  a  spring  of  com- 
mon water. 

Springs  of  water  impregnated  with  carbonic  acid 
occur  at  Schwalheim,  at  a  very  short  distance  from 
the  layers  of  wood  coal  at  Dorheim.  M.  Wilhelmi 
observed  some  time  since,  that  they  are  formed  of 
common  spring  water  which  ascends  from  below,  and 
of  carbonic  acid  which  issues  from  the  sides  of  the 
spring.  The  same  fact  has  been  shown  to  be  the 
case  in  the  famed  Fachinger  spring,  by  M.  Schapper. 

The  carbonic  acid  gas  from  the  springs  in  the 
Eifel,  is,  according  to  BischofF,  seldom  mixed  with 
nitrogen  or  oxygen,  and  is  probably  produced  in  a 
manner  similar  to  that  just  described.  At  any  rate 
the  air  does  not  appear  to  take  any  part  in  the  for- 
mation of  these  acidulous  springs.  Their  carbonic 
acid  has  evidently  not  been  formed  either  by  a  com- 
bustion at  high  or  low  temperatures ;  for  if  it  were 
so,  the  gas  resulting  from  the  combustion  would  ne- 
cessarily be  mixed  with  |  of  nitrogen,  but  it  does 
not  contain  a  trace  of  this  element.  The  bubbles  of 
gas  which  escape  from  these  springs  are  absorbed 
by  caustic  potash,  with  the  exception  of  a  residuum 
too  small  to  be  appreciated. 

The  wood  coal  of  Dorheim  and  Salzhausen  must 
have  been  formed  in  the  same  way  as  that  of  the 
neighboring  village  of  Laubach ;  and  since  the  latter 
contains  the  exact  elements  of  woody  fibre,  minus  a 


INTO  BROWN  OR  WOOD  COAL.  371 

certain  quantity  of  carbonic  acid,  its  composition 
indicates  very  plainly  the  manner  in  which  it  has 
been  produced. 

The  coal  of  the  upper  bed  is  subjected  to  an  in- 
cessant decay  by  the  action  of  the  air,  by  means  of 
which  its  hydrogen  is  removed  in  the  same  manner 
as  in  the  decay  of  wood.  This  is  recognised  by  the 
way  in  which  it  burns,  and  by  the  formation  of  car- 
bonic acid  in  the  mines. 

The  gases  which  are  formed  in  mines  of  wood  coal, 
and  cause  danger  in  their  working,  are  not  combus- 
tible or  inflammable  as  in  mines  of  mineral  coal ; 
but  they  consist  generally  of  carbonic  acid  gas,  and 
are  very  seldom  intermixed  with  combustible  gases. 

Wood  coal  from  the  middle  bed  of  the  strata  at 
Ringkuhl  gave  on  analysis  65*40,  —  64*01  carbon  and 
4*75,  —  4*76*  hydrogen;  the  proportion  of  carbon 
here  is  the  same  as  in  specimens  procured  from 
greater  depths,  but  that  of  the  hydrogen  is  much 
less. 

Wood  and  mineral  coal  are  always  accompanied 
by  iron  pyrites  (sulphuret  of  iron)  or  zinc  blende 
(sulphuret  of  zinc);  which  minerals  are  still  formed 
from  salts  of  sulphuric  acid,  with  iron  or  zinc,  during 
the  putrefaction  of  all  vegetable  matter.  It  is  pos- 
sible, that  the  oxygen  of  the  sulphates  in  the  layers 
of  wood  coal  is  the  means  by  which  the  removal  of 
the  hydrogen  is  effected,  since  wood  coal  contains 
less  of  this  element  than  wood. 

According  to  the  analysis  of  Richardson  and  Reg- 
nault,  the  composition  of  the  combustible  materials 
in  splint  coal  from  Newcastle,  and  cannel  coal  from 
Lancashire,  is  expressed  by  the  formula  C24  H13  O. 
When  this  is  compared  with  the  composition  of 
woody  fibre,  it  appears  that  these  coals  are  formed 
from  its  elements,  by  the  removal  of  a  certain  quan- 
tity of  carburetted  hydrogen  and  carbonic  acid   in 

*  The  analysis  of  brown  coal  from  Ringkuhl,  as  well  as  all  those  of 
the  same  substance  given  in  this  work,  have  been  executed  in  this  labo- 
ratory by  M.  Kiihnert  of  Cassel.  —  L. 


372  CONVERSION  OF  WOOD  INTO  MINERAL  COAL. 

the  form  of  combustible  oils.     The  composition  of 

both  of  these   coals  is  obtained  by  the  subtraction 

of  3   atoms   of  carburetted    hydrogen,  3  atoms   of 

water,  and  9  atoms  of  carbonic  acid  from  the  formula 

of  wood. 

C36H22  022  =  wood 

C12    H9  021 


3  atoms  of  carburetted  hydrogen  C  3    H6 
3  atoms  of  water         .  .      H  3    03 

9  atoms  of  carbonic  acid    .  C  9  018 


Mineral  coal         C24    H13  O 

Carburetted  hydrogen  generally  accompanies  all 
mineral  coal;  other  varieties  of  coal  contain  volatile 
oils,  which  may  be  separated  by  distillation  with 
water.  (Reichenbach.)  The  origin  of  naphtha  is 
owing  to  a  similar  process  of  decomposition.  Caking 
coal  from  Caresfield,  near  Newcastle,  contains  the 
elements  of  cannel  coal,  minus  the  constituents  of 
defiant  gas  C4  H4. 

The  inflammable  gases  which  stream  out  of  clefts 
in  the  strata  of  mineral  coal,  or  in  rocks  of  the  coal 
formations,  always  contain  carbonic  acid,  according 
to  a  recent  examination  by  BischofF,  and  also  car- 
buretted hydrogen,  nitrogen,  and  defiant  gas ;  the 
last  of  which  had  not  been  observed,  until  its  ex- 
istence in  these  gases  was  pointed  out  by  Bischoff. 
The  analysis  of  fire-damp,  after  it  had  been  treated 
with  caustic  potash,  showed  its  constituents  to  be. 

Gas  from  an 

abandoned  Gerbard's  pas-  Gas  from  a 

mine  near  sage  near  Lu-  mine    near 

Wallesweiler.  isenthal.  Liekwege. 

Vol.                     Vol.  Vol. 

Light  carburetted  hydrogen  91-36                  8308  79-10 

defiant  gas.            .      6-32                     1-98  16-11 

Nitrogen  gas    .           .  2-32                  14-94  4-79 

100-00  10000  10000 

The  evolution  of  these  gases  proves,  that  changes 
are  constantly  proceeding  in  the  coal. 

It  is  obvious  from  this,  that  a  continual  removal 
of  oxygen  in  the  form  of  carbonic  acid  is  effected 
from  layers  of  wood  coal,  in  consequence  of  which 
the  wood  must  approach  gradually  to  the  composition 


POISONS,  CONTAGIONS,  MIASMS.  373 

of  mineral  coal.  Hydrogen,  on  the  contrary,  is  dis- 
engaged from  the  constituents  of  mineral  coal  in  the 
form  of  a  compound  of  carbo-hydrogen ;  a  complete 
removal  of  all  the  hydrogen  would  convert  coal  into 
anthracite. 

The  formula  C36  H22  022,  which  is  given  for 
wood,  has  been  chosen  as  the  empirical  expression 
of  the  analysis,  for  the  purpose  of  bringing  all  the 
transformations,  which  woody  fibre  is  capable  of 
undergoing,  under  one  common  point  of  view. 

Now,  although  the  correctness  of  this  formula 
must  be  doubted,  until  we  know  with  certainty  the 
true  constitution  of  woody  fibre,  this  cannot  have 
the  smallest  influence  on  the  account  given  of  the 
changes  to  which  woody  fibre  must  necessarily  be 
subjected  in  order  to  be  converted  into  wood  or 
mineral  coal.  The  theoretical  expression  refers  to 
the  quantity,  the  empirical  merely  to  the  relative  pro- 
portion in  which  the  elements  of  a  body  are  united. 
Whatever  form  the  first  may  assume,  the  empirical 
expression  must  always  remain  unchanged. 


CHAPTER   Xm. 

ON  POISONS,  CONTAGIONS,  AND  MIASMS. 

A  GREAT  many  chemical  compounds,  some  derived" 
from  inorganic  nature,  and  others  formed  in  animals 
and  plants,  produce  peculiar  changes  or  diseases  in 
the  living  animal  organism.  They  destroy  the  vital 
functions  of  individual  organs;  and  when  their  ac- 
tion attains  a  certain  degree  of  intensity,  death  is 
the  consequence. 

The  action  of  inorganic  compounds,  such  as  acids, 
alkalies,  metallic  oxides,  and  salts,  can  in  most  cases 
be  easily  explained.  They  either  destroy  the  con- 
tinuity of  particular  organs,  or  they  enter  into  com- 

32 


374  POISONS,  CONTAGIOxNS,  MIASMS. 

bination  with  their  substance.  The  action  of  sul- 
phuric, muriatic,  and  oxalic  acids,  hydrate  of  potash, 
and  all  those  substances  which  produce  the  direct 
destruction  of  the  organs  with  which  they  come 
into  contact,  may  be  compared  to  a  piece  of  iron, 
which  can  cause  death  by  inflicting  an  injury  on  par- 
ticular organs,  either  when  heated  to  redness,  or 
when  in  the  form  of  a  sharp  knife.  Such  substances 
are  not  poisons  in  the  limited  sense  of  the  word,  for 
their  injurious  action  depends  merely  upon  their 
condition. 

The  action  of  the  proper  inorganic  poisons  is 
owing,  in  most  cases,  to  the  formation  of  a  chemical 
compound  by  the  union  of  the  poison  with  the  con- 
stituents of  the  organ  upon  which  it  acts ;  it  is 
owing  to  an  exercise  of  a  chemical  affinity  more 
powerful  than  the  vitality  of  the  organ. 

It  is  well  to  consider  the  action  of  inorganic  sub- 
stances in  general,  in  order  to  obtain  a  clear  con- 
ception of  the  mode  of  action  of  those  which  are 
poisonous.  We  find  that  certain  soluble  compounds, 
when  presented  to  different  parts  of  the  body,  are 
absorbed  by  the  blood,  whence  they  are  again  elim- 
inated by  the  organs  of  secretion,  either  in  a  changed 
or  in  an  unchanged  state. 

Iodide  of  potassium,  sulpho-cyanuret  of  potassium, 
ferro-cyanuret  of  potassium,  chlorate  of  potash,  sili- 
cate of  potash,  and  all  salts  with  alkaline  bases, 
when  administered  internally  to  man  and  animals  in 
dilute  solutions,  or  applied  externally,  may  be  again 
detected  in  the  blood,  sweat,  chyle,  gall,  and  splenic 
veins ;  but  all  of  them  are  finally  excreted  from  the 
body  through  the  urinary  passages. 

Each  of  these  substances,  in  its  transit,  produces 
a  peculiar  disturbance  in  the  organism, — in  other 
words,  they  exercise  a  medicinal  action  upon  it,  but 
they  themselves  suffer  no  decomposition.  If  any  of 
these  substances  enter  into  combination  with  any 
part  of  the  body,  the  union  cannot  be  of  a  perma- 
nent kind ;  for  their  reappearance  in  the  urine  shows 


EFFECTS  OF  SALTS  ON  THE  ORGANISM.  375 

that  any  compounds  thus  formed  must  have  been 
again  decomposed  by  the  vital  processes. 

Neutral  citrates,  acetates,  and  tartrates  of  the 
alkalies,  suffer  change  in  their  passage  through  the 
organism.  Their  bases  can  indeed  be  detected  in 
the  urine,  but  the  acids  have  entirely  disappeared, 
and  are  replaced  by  carbonic  acid  which  has  united 
with  the  bases.     (Gilbert  Blane  and  Wohler.) 

The  conversion  of  these  salts  of  organic  acids 
into  carbonates,  indicates  that  a  considerable  quan- 
tity of  oxygen  must  have  united  with  their  elements. 
In  order  to  convert  1  equivalent  of  acetate  of  potash 
into  the  carbonate  of  the  same  base,  8  equivalents 
of  oxygen  must  combine  with  it,  of  which  either  2 
or  4  equivalents  (according  as  an  acid  or  neutral 
salt  is  produced)  remain  in  combination  with  the 
alkali ;  whilst  the  remaining  6  or  4  equivalents  are 
disengaged  as  free  carbonic  acid.  There  is  no  evi- 
dence presented  by  the  organism  itself,  to  which 
these  salts  have  been  administered,  that  any  of  its 
proper  constituents  have  yielded  so  great  a  quantity 
of  oxygen  as  is  necessary  for  their  conversion  into 
carbonates.  Their  oxidation  can,  therefore,  only  be 
ascribed  to  the  oxygen  of  the  air. 

During  the  passage  of  these  salts  through  the 
lungs,  their  acids  take  part  in  the  peculiar  process 
of  eremacausis  which  proceeds  in  that  organ;  a  cer- 
tain quantity  of  the  oxygen  gas  inspired  unites  with 
their  constituents,  and  converts  their  hydrogen  into 
water,  and  their  carbon  into  carbonic  acid.  Part  of 
this  latter  product  (1  or  2  equivalents)  remains  in 
combination  with  the  alkaline  base,  forming  a  salt 
which  suffers  no  further  change  by  the  process  of 
oxidation;  and  it  is  this  salt  which  is  separated  by 
the  kidneys  or  liver. 

It  is  manifest,  that  the  presence  of  these  organic 
salts  in  the  blood  must  produce  a  change  in  the  pro- 
cess of  respiration.  A  part  of  the  oxygen  inspired, 
which  usually  combines  with  the  constituents  of  the 
blood,  must,  when   they  are   present,  combine   with 


376  POISONS,   CONTAGIONS,  MIASMS. 

their  acids,  and  thus  be  prevented  from  performing 
its  usual  office.  The  immediate  consequence  of  this 
must  be  the  formation  of  arterial  blood  in  less  quan- 
tity, or  in  other  words,  the  process  of  respiration 
must  be  retarded. 

Neutral  acetates,  tartrates,  and  citrates  placed  in 
contact  with  the  air,  and  at  the  same  time  with 
animal  or  vegetable  bodies  in  a  state  of  eremacausis, 
produce  exactly  the  same  effects  as  we  have  de- 
scribed them  to  produce  in  the  lungs.  They  partici- 
pate in  the  process  of  decay,  and  are  converted  into 
carbonates  just  as  in  the  living  body.  If  impure 
solutions  of  these  salts  in  water  are  left  exposed 
to  the  air  for  any  length  of  time,  their  acids  are 
gradually  decomposed,  and  at  length  entirely  disap- 
pear. 

Free  mineral  acids,  or  organic  acids  which  are  not 
volatile,  and  salts  of  mineral  acids  with  alkaline 
bases,  completely  arrest  decay  when  added  to  decay- 
ing matter  in  sufficient  quantity ;  and  when  their 
quantity  is  small,  the  process  of  decay  is  protracted 
and  retarded.  They  produce  in  living  bodies  the 
same  phenomena  as  the  neutral  organic  salts,  but 
their  action  depends  upon  a  different  cause. 

The  absorption  by  the  blood  of  a  quantity  of  an 
inorganic  salt  sufficient  to  arrest  the  process  of 
eremacausis  in  the  lungs,  is  prevented  by  a  very 
remarkable  property  of  all  animal  membranes,  skin, 
cellular  tissue,  muscular  fibre,  &c. ;  namely,  by  their 
incapability  of  being  permeated  by  concentrated 
saline  solutions.  It  is  only  when  these  solutions 
are  diluted  to  a  certain  degree  with  water  that  they 
are  absorbed  by  animal  tissues. 

A  dry  bladder  remains  more  or  less  dry  in  satu- 
rated solutions  of  common  salt,  nitre,  ferro-cyanuret 
of  potassium,  sulpho-cyanuret  of  potassium,  sulphate 
of  magnesia,  chloride  of  potassium,  and  sulphate  of 
soda.  These  solutions  run  off  its  surface  in  the 
same  manner  as  water  runs  from  a  plate  of  glass 
besmeared  with  tallow. 


EFFECTS  OF  SALTS  ON  THE  ORGANISM.  377 

Fresh  flesh,  over  which  salt  has  been  strewed,  is 
found  after  24  hours'  swimming  in  brine,  although 
not  a  drop  of  water  has  been  added.  The  water 
has  been  yielded  by  muscular  fibre  itself,  and  having 
dissolved  the  salt  in  immediate  contact  with  it,  and 
I  thereby  lost  the  power  of  penetrating  animal  sub- 
stances, it  has  on  this  account  separated  from  the 
flesh.  The  water  still  retained  by  the  flesh  contains 
a  proportionally  small  quantity  of  salt,  having  that 
degree  of  dilution  at  which  a  saline  fluid  is  capable 
of  penetrating  animal  substances. 

This  property  of  animal  tissues  is  taken  advantage 
of  in  domestic  economy  for  the  purpose  of  removing 
so  much  water  from  meat  that  a  sufficient  quantity  is 
not  left  to  enable  it  to  enter  into  putrefaction.    . 

In  respect  of  this  physical  property  of  animal 
tissues,  alcohol  resembles  the  inorganic  salts.  It  is 
incapable  of  moistening,  that  is,  of  penetrating,  ani- 
mal tissues,  and  possesses  such  an  affinity  for  water 
as  to  extract  it  from  moist  substances. 

When  a  solution  of  a  salt,  in  a  certain  degree  of 
dilution,  is  introduced  into  the  stomach,  it  is  ab- 
sorbed ;  but  a  concentrated  saline  solution,  in  place 
of  being  itself  absorbed,  extracts  water  from  the 
organ,  and  a  violent  thirst  ensues.  Some  inter- 
change of  water  and  salt  takes  place  in  the  stomach ; 
the  coats  of  this  viscus  yield  water  to  the  solution, 
a  part  of  which  having  previously  become  sufficiently 
diluted,  is,  on  the  other  hand,  absorbed.  But  the 
greater  part  of  the  concentrated  solution  of  salt 
remains  unabsorbed,  and  is  not  removed  by  the 
urinary  passages  ;  it  consequently  enters  the  intes- 
tines and  intestinal  canal,  where  it  causes  a  dilution 
of  the  solid  substances  deposited  there,  and  thus 
acts  as  a  purgative. 

Each  of  the  salts  just  mentioned  possesses  this 
purgative  action,  which  depends  on  a  physical  prop- 
erty shared  by  all  of  them;  but  besides  this  they 
exercise  a  medicinal  action,  because  every  part  of 
32* 


378  POISONS,  CONTAGIONS,  MIASMS. 

the  organism  with  which  they  come  in  contact  ab- 
sorbs a  certain  quantity  of  them. 

The  composition  of  the  salts  has  nothing  to  do 
with  their  purgative  action ;  it  is  quite  a  matter  of 
indifference  as  far  as  the  mere  production  of  this 
action  is  concerned  (not  as  to  its  intensity),  whether 
the  base  be  potash  or  soda,  or  in  many  cases  lime 
and  magnesia;  and  whether  the  acid  be  phosphoric, 
sulphuric,  nitric,  or  hydrochloric. 

Besides,  these  salts,  the  action  of  which  does  not 
depend  upon  their  power  of  entering  into  combina- 
tion with  the  component  parts  of  the  organism,  there 
is  a  large  class  of  others  which,  when  introduced 
into  the  living  body  effect  changes  of  a  very  different 
kind,  and  produce  diseases  or  death,  according  to 
the  nature  of  these  changes,  without  effecting  a 
visible  lesion  of  any  organs. 

These  are  the  true  inorganic  poisons,  the  action 
of  which  depends  upon  their  power  of  forming  per- 
manent compounds  with  the  substance  of  the  mem- 
branes, and  muscular  fibre. 

Salts  of  lead,  iron,  bismuth,  copper,  and  mercury, 
belong  to  this  class. 

When  solutions  of  these  salts  are  treated  with  a 
sufficient  quantity  of  albumen,  milk,  muscular  fibre, 
and  animal  membranes,  they  enter  into  combination 
with  those  substances,  and  lose  their  own  solubility ; 
while  the  water  in  which  they  were  dissolved  loses 
all  the  salt  which  it  contained. 

The  salts  of  alkaline  bases  extract  water  from 
animal  substances ;  whilst  the  salts  of  the  heavy 
metallic  oxides  are,  on  the  contrary,  extracted  from 
the  water,  for  they  enter  into  combination  with  the 
animal  matters. 

Now,  when  these  substances  are  administered  to 
an  animal,  they  lose  their  solubility  by  entering  into 
combination  with  the  membranes,  cellular  tissue,  and 
muscular  fibre  ;  but  in  very  few  cases  can  they  reach 
the  blood.  All  experiments  instituted  for  the  pur- 
pose of  determining  whether  they  pass  into  the  urine 


INORGANIC  POISONS.  379 


* 


have  failed  to  detect  them  in  that  secretion.  In  fact, 
during  their  passage  through  the  organism,  they 
come  into  contact  with  many  substances  by  which 
they  are  retained. 

The  action  of  corrosive  sublimate  and  arsenious 
acid  is  very  remarkable  in  this  respect.  It  is  known 
that  these  substances  possess,  in  an  eminent  degree, 
the  property  of  entering  into  combination  with  all 
parts  of  animal  and  vegetable  bodies,  rendering  them 
at  the  same  time  insusceptible  of  decay  or  putrefac- 
tion. Wood  and  cerebral  substance  are  both  bodies 
which  undergo  change  with  great  rapidity  and  facili- 
ty when  subject  to  the  influence  of  air  and  water; 
but  if  they  are  digested  for  some  time  with  arsenious 
acid  or  corrosive  sublimate,  they  may  subsequently 
be  exposed  to  all  the  influences  of  the  atmosphere 
without  altering  in  color  or  appearance. 

It  is  further  known,  that  those  parts  of  a  body 
which  come  in  contact  with  these  substances  during 
poisoning,  and  which  therefore  enter  into  combina- 
tion with  them,  do  not  afterwards  putrefy ;  so  that 
there  can  be  no  doubt  regarding  the  cause  of  their 
poisonous  qualities. 

It  is  obvious,  that  if  arsenious  acid  and  corrosive 
sublimate  are  not  prevented  by  the  vital  principle 
from  entering  into  combination  with  the  component 
parts  of  the  body,  and  consequently  from  rendering 
them  incapable  of  decay  and  putrefaction,  they  must 
deprive  the  organs  of  the  principal  property  which 
appertains  to  their  vital  condition,  viz.  that  of  suffer- 
ing and  eff*ecting  transformations ;  or,  in  other  words, 
organic  life  must  be  destroyed.  If  the  poisoning  is 
merely  superficial,  and  the  quantity  of  the  poison  so 
small  that  only  individual  parts  of  the  body  which 
are  capable  of  being  regenerated  have  entered*  into 
combination  with  it,  then  eschars  are  produced,  —  a 
phenomenon  of  a  secondary  kind,  —  the  compounds 
of  the  dead  tissues  with  the  poison  being  thrown  off" 
by  the  healthy  parts.  From  these  considerations  it 
may  readily  be  inferred,  that  all  internal   signs  of 


380  POISONS,  CONTAGIONS,  MIASMS. 

poisoning  are  variable  and  uncertain;  for  cases  may 
happen,  in  which  no  apparent  indication  of  change 
can  be  detected  by  simple  observations  of  the  parts, 
because,  as  has  been  already  remarked,  death  may 
occur  without  the  destruction  of  any  organs. 

When  arsenious  acid  is  administered  in  solution, 
it  may  enter  into  the  blood.  If  a  vein  is  exposed 
and  surrounded  with  a  solution  of  this  acid,  every 
blood-globule  will  combine  with  it,  that  is,  will  be- 
come poisoned. 

The  compounds  of  arsenic,  which  have  not  the 
property  of  entering  into  combination  with  the  tis- 
sues of  the  organism,  are  without  influence  on  life, 
even  in  large  doses.  Many  insoluble  basic  salts  of 
arsenious  acid  are  known  not  to  be  poisonous.  The 
substance  called  alkargen,  discovered  by  Bunsen, 
has  not  the  slightest  injurious  action  upon  the  organ- 
ism ;  yet  it  contains  a  very  large  quantity  of  arsenic, 
and  approaches  very  closely  in  composition  to  the 
organic  arsenious  compounds  found  in  the  body. 

These  considerations  enable  us  to  fix  with  tolera- 
ble certainty  the  limit  at  which  the  above  substances 
cease  to  act  as  poisons.  For  since  their  combina- 
tion with  organic  matters  must  be  regulated  by 
chemical  laws,  death  will  inevitably  result,  when  the 
organ  in  contact  with  the  poison  finds  sufficient  of  it 
to  unite  with  atom  for  atom;  whilst  if  the  poison  is 
present  in  smaller  quantity,  a  part  of  the  organ  will 
retain  its  vital  functions. 

According  to  the  experiments  of  Mulder,*  the 
equivalent  in  which  fibrin  combines  with  muriatic 
acid,  and  with  the  oxides  of  lead  and  copper,  is 
expressed  by  the  number  6361.  It  may  be  assumed, 
therefore,  approximatively,  that  a  quantity  of  fibrin 
corresponding  to  the  number  6361  combines  with  1 
equivalent  of  arsenious  acid,  or  1  equivalent  of  cor- 
rosive sublimate. 

When  6361  parts  of  anhydrous  fibrin  are  combined 

*  PoggendorfTs  Annalen,  Band  xl.  S.  259. 


INORGANIC  POISONS.  381 

with  30,000  parts  of  water,  it  is  in  the  state  in  which 
it  is  contained  in  muscular  fibre  or  blood  in  the 
human  body.  100  grains  of  fibrin  in  this  condition 
would  form  a  neutral  compound  of  equal  equivalents 
with  3^  grains  of  arsenious  acid,  and  5  grains  of 
corrosive  sublimate. 

The  atomic  weight  of  the  albumen  of  eggs  and  of 
the  blood  deduced  from  the  analysis  of  the  compound 
which  it  forms  with  oxide  of  silver  is  7447,  and  that 
of  animal  p-elatin  5652. 

100  grains  of  albumen  containing  all  the  water 
with  which  it  is  combined  in  the  living  body,  should 
consequently  combine  with  1^  grain  of  arsenious 
acid. 

These  proportions,  which  may  be  considered  as 
the  highest  which  can  be  adopted,  indicate  the  re- 
markably high  atomic  weights  of  animal  substances, 
and  at  the  same  time  teach  us,  what  very  small  quan- 
tities of  arsenious  acid  or  corrosive  sublimate  are 
requisite  to  produce  deadly  effects. 

All  substances  administered  as  antidotes  in  cases 
of  poisoning,  act  by  destroying  the  power  which 
arsenious  acid  and  corrosive  sublimate  possess,  of 
entering  into  combination  with  animal  matters,  and 
of  thus  acting  as  poisons.  Unfortunately  no  other 
body  surpasses  them  in  that  power,  and  the  com- 
pounds which  they  form  can  only  be  broken  up  by 
affinities  so  energetic,  that  their  action  is  as  injuri- 
ous as  that  of  the  above-named  poisons  themselves. 
The  duty  of  the  physician  consists,  therefore,  in  his 
causing  those  parts  of  the  poison  which  may  be  free 
and  still  uncombined,  to  enter  into  combination  with 
some  other  body,  so  as  to  produce  a  compound  inca- 
pable of  being  decomposed  or  digested  in  the  same 
conditions.  Hydrated  peroxide  of  iron  is  an  inval- 
uable substance  for  this  purpose.* 

When  the  action  of  arsenious  acid  or  corrosive 
sublimate  is   confined  to  the   surface   of   an  organ, 

**  On  the  preparation,  &c.,  of  this  antidote,  see  Appendix. 


382  POISONS,   CONTAGIONS,  MIASMS. 

those  parts  only  are  destroyed  which  enter  into  com- 
bination with  it;  an  eschar  is  formed,  which  is  grad- 
ually thrown  off. 

Soluble  salts  of  silver  would  be  quite  as  deadly  a 
poison  as  corrosive  sublimate,  did  not  a  cause  exist 
in  the  human  body  by  which  their  action  is  prevented, 
unless  their  quantity  is  very  great.  This  cause  is 
the  presence  of  common  salt  in  all  animal  liquids. 
Nitrate  of  silver,  it  is  well  known,  combines  with 
animal  substances,  in  the  same  manner  as  corrosive 
sublimate,  and  the  compounds  formed  by  both  are 
exactly  similar  in  the  character  of  being  incapable 
of  decay  or  putrefaction. 

When  nitrate  of  silver  in  a  state  of  solution  is 
applied  to  skin  or  muscular  fibre,  it  combines  with 
them  instantaneously;  animal  substances  dissolved 
in  any  liquid  are  precipitated  by  it,  and  rendered 
insoluble,  or,  as  it  is  usually  termed,  they  are  coagu- 
lated. The  compounds  thus  formed  are  colorless, 
and  so  stable,  that  they  cannot  be  decomposed  by 
other  powerful  chemical  agents.  They  are  blackened 
by  exposure  to  light,  like  all  other  compounds  of 
silver,  in  consequence  of  a  part  of  the  oxide  of  silver 
which  they  contain  being  reduced  to  the  metallic 
state.  Parts  of  the  body  which  have  united  with 
salts  of  silver  no  longer  belong  to  the  living  organ- 
ism, for  their  vital  functions  have  been  arrested  by 
combination  with  oxide  of  silver ;  and  if  they  are 
capable  of  being  reproduced,  the  neighboring  living 
structures  throw  them  off  in  the  form  of  an  eschar. 

When  nitrate  of  silver  is  introduced  into  the 
stomach,  it  meets  with  common  salt  and  free  muriatic 
acid ;  and  if  its  quantity  is  not  too  great,  it  is  im- 
mediately converted  into  chloride  of  silver,  —  a  sub- 
stance which  is  absolutely  insoluble  in  pure  water. 
In  a  solution  of  salt  or  muriatic  acid,  however, 
chloride  of  silver  does  dissolve  in  extremely  minute 
quantity ;  and  it  is  this  small  part  which  exercises 
a  medicinal  influence  when  nitrate  of  silver  is  admin- 
istered ;    the  remaining  chloride  of  silver  is  elimi- 


INORGANIC  POISONS.  383 

nated  from  the  body  in  the  ordinary  way.  Solubility 
is  necessary  to  give  efficacy  to  any  substance  in  the 
human  body. 

The  soluble  salts  of  lead  possess  many  properties 
in  common  with  the  salts  of  silver  and  mercury ;  but 
all  compounds  of  lead  with  organic  matters  are 
capable  of  decomposition  by  dilute  sulphuric  acid. 
The  disease  called  painter^s  colic  is  unknown  in  all 
manufactories  of  white  lead  in  which  the  workmen 
are  accustomed  to  take  as  a  preservative  sulphuric 
acid-lemonade  (a  solution  of  sugar  rendered  acid  by 
sulphuric  acid). 

The  organic  substances  which  have  combined  in 
the  living  body  with  metallic  oxides  or  metallic  salts, 
lose  their  property  of  imbibing  water  and  retaining 
it,  without  at  the  same  time  being  rendered  incapa- 
ble of  permitting  liquids  to  penetrate  through  their 
pores.  A  strong  contraction  and  shrinking  of  the 
surface  is  the  general  effect  of  contact  with  these 
metallic  bodies.  But  corrosive  sublimate,  and  several 
of  the  salts  of  lead,  possess  a  peculiar  property,  in 
addition  to  those  already  mentioned.  When  they  are 
present  in  excess,  they  dissolve  the  first  formed 
insoluble  compounds,  and  thus  produce  an  effect 
quite  the  reverse  of  contraction,  namely,  a  softening 
of  the  part  of  the  body  on  which  they  have  acted. 

Salts  of  oxide  of  copper,  even  when  in  combina- 
tion with  the  most  powerful  acids,  are  reduced  by 
many  vegetable  substances,  particularly  such  as  sugar 
and  honey,  either  into  metallic  copper,  or  into  the 
red  suboxide,  neither  of  which  enters  into  combina- 
tion with  animal  matter.  It  is  well  known  that  sugar 
has  been  long  employed  as  the  most  convenient 
antidote  for  poisoning  by  copper. 

With  respect  to  some  other  poisons,  namely,  hy- 
drocyanic acid  and  the  organic  bases  strychnia  and 
brucia,  we  are  acquainted  with  no  facts  calculated  to 
elucidate  the  nature  of  their  action.  It  may,  how- 
ever, be  presumed  with  much  certainty,  that  experi- 
ments upon  their  mode  of  action  on  different  animal 


384  POISONS,   CONTAGION^,  MIASMS. 

substances  would  very  quickly  lead  td  the  most 
satisfactory  conclusions  regarding  the  cause  of  their 
poisonous  effects. 

There  is  a  peculiar  class  of  substances,  which  are 
generated  during  certain  processes  of  decomposition, 
and  which  act  upon  the  animal  economy  as  deadly 
poisons,  not  on  account  of  their  power  of  entering 
into  combination  with  it,  or  by  reason  of  their  con- 
taining a  poisonous  material,  but  solely  by  virtue  of 
their  peculiar  condition. 

In  order  to  attain  a  clear  conception  of  the  mode 
of  action  of  these  bodies,  it  is  necessary  to  call  to 
mind  the  cause  on  which  we  have  shown  the  phe- 
nomena of  fermentation,  decay,  and  putrefaction  to 
depend. 

This  cause  may  be  expressed  by  the  following 
law,  long  since  proposed  by  La  Place  and  Berthollet, 
although  its  truth  with  respect  to  chemical  phenom- 
ena has  only  lately  been  proved.  "  A  molecule  set 
in  motion  by  any  power  can  impart  its  own  m^otion  to 
another  molecule  with  which  it  may  be  in  cotitact.^^ 

This  is  a  law  of  dynamics,  the  operation  of  which 
is  manifest  in  all  cases,  in  which  the  resistance 
{force,  affinity,  or  cohesion)  opposed  to  the  motion  is 
not  sufficient  to  overcome  it. 

We  have  seen  that  ferment  or  yeast  is  a  body  in 
the  state  of  decomposition,  the  atoms  of  which,  con- 
sequently, are  in  a  state  of  motion  or  transposition. 
Yeast  placed  in  contact  with  sugar  communicates  to 
the  elements  of  that  compound  the  same  state,  in 
consequence  of  which,  the  constituents  of  the  sugar 
arrange  themselves  into  new  and  simpler  forms,  = 
namely,  into  alcohol  and  carbonic  acid.  In  these 
new  compounds  the  elements  are  united  together  by 
stronger  affinities  than  they  were  in  the  sugar,  and 
therefore  under  the  conditions  in  which  they  were  in 
produced  further  decomposition  is  arrested. 

We  know,  also,  that  the  elements  of  sugar  assume; 
totally  different  arrangements,  when  the  substances 
which  excite   their  transposition  are  in  a  different 


PUTRID  POISONS.  385 

state  of  decomposition  from  the  yeast  just  mentioned. 
Thus,  when  sugar  is  acted  on  by  rennet  or  putrefy- 
ing vegetable  juices,  it  is  not  converted  into  alcohol 
and  carbonic  acid,  but  into  lactic  acid,  mannite,  and 
gum. 

Again,  it  has  been  shown,  that  yeast  added  to  a 
solution  of  pure  sugar  gradually  disappears,  but  that 
when  added  to  vegetable  juices  which  contain  gluten 
as  well  as  sugar,  it  is  reproduced  by  the  decomposi- 
tion of  the  former  substance. 

The  yeast  with  which  these  liquids  are  made  to 
ferment,  has  itself  been  originally  produced  from 
gluten. 

The  conversion  of  gluten  into  yeast  in  these  veg- 
etable juices  is  dependent  on  the  decomposition 
(fermentation)  of  sugar ;  for,  when  the  sugar  has 
completely  disappeared,  any  gluten  which  may  still 
remain  in  the  liquid  does  not  suffer  change  from 
contact  with  the  newly-deposited  yeast,  but  retains 
all  the  characters  of  gluten. 

Yeast  is  a  product  of  the  decomposition  of  gluten; 
but  it  passes  into  a  second  stage  of  decomposition 
when  in  contact  with  water.  On  account  of  its  being 
in  this  state  of  further  change,  yeast  excites  fermen- 
tation in  a  fresh  solution  of  sugar,  and  if  this  second 
saccharine  fluid  should  contain  gluten,  (should  it  be 
wort^  for  example,)  yeast  is  again  generated  in  con- 
sequence of  the  transposition  of  the  elements  of  the 
sugar  exciting  a  similar  change  in  this  gluten. 

After  this  explanation,  the  idea  that  yeast  repro- 
duces itself  as  seeds  reproduce  seeds,  cannot  for  a 
moment  be  entertained. 

From  the  foregoing  facts  it  follows,  that  a  body 
in  the  act  of  decomposition  (it  may  be  named  the 
exciter)^  added  to  a  mixed  fluid  in  which  its  constit- 
uents are  contained,  can  reproduce  itself  in  that 
fluid,  exactly  in  the  same  manner  as  new  yeast  is 
produced  when  yeast  is  added  to  liquids  containing 
gluten.  This  must  be  more  certainly  effected  when 
the  liquid  acted  upon  contains  the  body  by  the  met- 
33 


386  POISONS,  CONTAGIONS,   MIASMS. 

amorphosis  of  which  the  exciter  has  been  originally 
formed. 

It  is  also  obvious,  that  if  the  exciter  be  able  to 
impart  its  own  state  of  transformation  to  one  only 
of  the  component  parts  of  the  mixed  liquid  acted 
upon,  its  own  reproduction  may  be  the  consequence 
of  the  decomposition  of  this  one  body. 

This  law  may  be  applied  to  organic  substances 
forming  part  of  the  animal  organism.  We  know  that 
all  the  constituents  of  these  substances  are  formed 
from  the  blood,  and  that  the  blood  by  its  nature  and 
constitution  is  one  of  the  most  complex  of  all  exist- 
ing matters. 

Nature  has  adapted  the  blood  for  the  reproduction 
of  every  individual  part  of  the  organism ;  its  princi- 
pal character  consists  in  its  component  parts  being 
subordinate  to  every  attraction.  These  are  in  a  per- 
petual state  of  change  or  transformation,  which  is 
effected  in  the  most  various  ways  through  the  in- 
fluence of  the  different  organs. 

The  individual  organs,  such  as  the  stomach,  cause 
all  the  organic  substances  conveyed  to  them  which 
are  capable  of  transformation  to  assume  new  forms. 
The  stomach  compels  the  elements  of  these  sub- 
stances to  unite  into  a  compound  fitted  for  the  for- 
mation of  the  blood.  But  the  blood  possesses  no 
power  of  causing  transformations ;  on  the  contrary, 
its  principal  character  consists  in  its  readily  suffering 
transformations ;  and  no  other  matter  can  be  com- 
pared in  this  respect  with  it. 

Now  it  is  a  well-known  fact,  that  when  blood, 
cerebral  substance,  gall,  pus,  and  other  substances 
in  a  state  of  putrefaction,  are  laid  upon  fresh 
wounds,  vomiting,  debility,  and  at  length  death, 
are  occasioned.  It  is  also  well  known,  that  bodies 
in  anatomical  rooms  frequently  pass  into  a  state  of 
decomposition  which  is  capable  of  imparting  itself 
to  the  living  body,  the  smallest  cut  with  a  knife, 
which  has  been  used  in  their  dissection,  producing 
in  these  cases  dangerous  consequences. 


PUTRID  POISONS.  387 

V 

The  poison  of  bad  sausages  belongs  to  this  class 
of  noxious  substances.  Several  hundred  cases  are 
known  in  which  death  has  occurred  from  the  use  of 
this  kind  of  food.  In  Wurtemberg,  especially,  these 
cases  are  very  frequent,  for  there  the  sausages  are 
prepared  from  very  various  materials.  Blood,  liver, 
bacon,  brains,  milk,  meal,  and  bread,  are  mixed  to- 
gether with  salt  and  spices  ;  the  mixture  is  then  put 
into  bladders  or  intestines,  and  after  being  boiled  is 
smoked. 

When  these  sausages  are  well  prepared,  they  may 
be  preserved  for  months,  and  furnish  a  nourishing, 
savoury  food;  but  when  the  spices  and  salt  are  de- 
ficient, and  particularly  when  they  are  smoked  too 
late  or  not  sufficiently,  they  undergo  a  peculiar  kind 
of  putrefaction,  which  begins  at  the  centre  of  the 
sausage.  Without  any  appreciable  escape  of  gas 
taking  place  they  become  paler  in  color,  and  more 
soft  and  greasy  in  those  parts  which  have  under- 
gone putrefaction,  and  they  are  found  to  contain  free 
lactic  acid,  or  lactate  of  ammonia,  products  which 
are  universally  formed  during  the  putrefaction  of 
animal  and  vegetable  matters. 

The  cause  of  the  poisonous  nature  of  these  sau- 
sages was  ascribed  at  first  to  hydrocyanic  acid,  and 
afterwards  to  sebacic  acid,  although  neither  of  these 
substances  had  been  detected  in  them.  But  sebacic 
acid  is  no  more  poisonous  than  benzoic  acid,  with 
which  it  has  so  many  properties  in  common ;  and  the 
symptoms  produced  are  sufficient  to  show  that  hy- 
drocyanic acid  is  not  the  poison. 

The  death  which  is  the  consequence  of  poisoning 
by  putrefied  sausages  succeeds  very  lingering  and 
remarkable  symptoms.  There  is  a  gradual  wasting 
of  muscular  fibre,  and  of  all  the  constituents  of  the 
body  similarly  composed;  the  patient  becomes  much 
emaciated,  dries  to  a  complete  mummy,  and  finally 
dies.  The  carcass  is  stiff  as  if  frozen,  and  is  not 
subject  to  putrefaction.     During  the  progress  of  the 


388  POISONS,  CONTAGIONS,  MIASMS. 

disease  the  saliva  becomes  viscous  and  acquires  an 
offensive  smell. 

Experiments  have  been  made  for  the  purpose  of 
ascertaining  the  presence  of  some  matter  in  the 
sausages  to  which  their  poisonous  action  could  be 
ascribed ;  but  ^no  such  matter  has  been  detected. 
Boiling  water  and  alcohol  completely  destroy  the 
poisonous  properties  of  the  sausages,  without  them- 
selves acquiring  similar  properties. 

Now  this  is  the  peculiar  character  of  all  substances 
which  exert  an  action  by  virtue  of  their  existing 
condition,  —  of  those  bodies  the  elements  of  which 
are  in  the  state  of  decomposition  or  transposition ;  a 
state  which  is  destroyed  by  boiling  water  and  alco- 
hol without  the  cause  of  the  influence  being  imparted 
to  those  liquids;  for  a  state  of  action  or  power  can- 
not be  preserved  in  a  liquid. 

Sausages,  in  the  state  here  described,  exercise  an 
action  upon  the  organism,  in  consequence  of  the 
stomach  and  other  parts  with  which  they  come  in 
contact  not  having  the  power  to  arrest  their  decom- 
position ;  and  entering  the  blood  in  some  way  or 
other,  while  still  possessing  their  whole  power,  they 
impart  their  peculiar  action  to  the  constituents  of 
that  fluid. 

The  poisonous  properties  of  decayed  sausages  are 
not  destroyed  by  the  stomach  as  those  of  the  small- 
pox virus  are.  All  the  substances  in  the  body  capa- 
ble of  putrefaction  are  gradually  decomposed  during 
the  course  of  the  disease,  and  after  death  nothing 
remains  except  fat,  tendons,  bones,  and  a  few  other 
substances,  which  are  incapable  of  putrefying  in  the 
conditions  afforded  by  the  body. 

It  is  impossible  to  mistake  the  modus  operandi  of 
this  poison,  for  Colin  has  clearly  proved  that  mus- 
cle, urine,  cheese,  cerebral  substance,  and  other 
matters,  in  a  state  of  putrefaction,  communicate 
their  own  state  of  decomposition  to  substances  much 
less  prone  to  change  of  composition  than  the  blood. 
When  placed  in  contact  with   a  solution  of  sugar, 


MORBID  POISONS.  .      389 

they  cause  its  putrefaction,  or  the  transposition  of 
its  elements  into  carbonic  acid  and  alcohol. 

When  putrefying  muscle  or  pus  is  placed  upon  a 
fresh  wound,  it  occasions  disease  and  death.  It  is 
obvious  that  these  substances  communicate  their 
own  state  of  putrefaction  to  the  sound  blood  from 
which  they  were  produced^  exactly  in  the  same  man- 
ner as  gluten  in  a  state  of  decay  or  putrefaction 
causes  a  similar  transformation  in  a  solution  of 
sugar. 

Poisons  of  this  kind  are  even  generated  by  the 
body  itself  in  particular  diseases.  In  small-pox, 
plague,  and  syphilis,  substances  of  a  peculiar  na- 
ture are  formed  from  the  constituents  of  the  blood. 
These  matters  are  capable  of  inducing  in  the  blood 
of  a  healthy  individual  a  decomposition  similar  to 
that  of  which  they  themselves  are  the  subjects ;  in 
other  words,  they  produce  the  same  disease.  The 
morbid  virus  appears  to  reproduce  itself  just  as  seeds 
appear  to  reproduce  seeds. 

The  mode  of  action  of  a  morbid  virus  exhibits 
such  a  strong  similarity  to  the  action  of  yeast  upon 
liquids  containing  sugar  and  gluten,  that  the  two 
processes  have  been  long  since  compared  to  one 
another,  although  merely  for  the  purpose  of  illustra- 
tion. But  when  the  phenomena  attending  the  action 
of  each  respectively  are  considered  more  closely,  it 
will  in  reality  be  seen  that  their  influence  depends 
upon  the  same  cause. 

In  dry  air,  and  in  the  absence  of  moisture,  all 
these  poisons  remain  for  a  long  time  unchanged ;  but 
when  exposed  to  the  air  in  the  moist  condition,  they 
lose  very  rapidly  their  peculiar  properties.  In  the 
former  case,  those  conditions  are  afforded  which 
arrest  their  decomposition  without  destroying  it ; 
in  the  latter,  all  the  circumstances  necessary  for  the 
completion  of  their  decomposition  are  presented. 

The  temperature  at  which  water  boils,  and  contact 
with  alcohol,  render  such  poisons  inert.  Acids,  salts 
of   mercury,  sulphurous   acid,  chlorine,  iodine,  bro- 

33* 


390  POISONS,  CONTAGIONS,  MUSMS. 

mine,  aromatic  substances,  volatile  oils,  and  partic- 
ularly empyreumatic  oils,  smoke,  and  a  decoction  of 
coffee,  completely  destroy  their  contagious  properties, 
in  some  cases  combining  with  them  or  otherwise 
effecting  their  decomposition.  Now  all  these  agents, 
without  exception,  retard  fermentation,  putrefaction 
and  decay,  and  when  present  in  sufficient  quantity, 
completely  arrest  these  processes  of  decomposition. 

A  peculiar  matter  to  which  the  poisonous  action 
is  due,  cannot,  we  have  seen,  be  extracted  from 
decayed  sausages ;  and  it  is  equally  impossible  to 
obtain  such  a  principle  from  the  virus  of  small-pox 
or  plague,  and  for  this  reason,  that  their  peculiar 
power  is  due  to  an  active  condition  recognisable  by 
our  senses,  only  through  the  phenomena  which  it 
produces. 

In  order  to  explain  the  effects  of  contagious  mat- 
ters, a  peculiar  principle  of  life  has  been  ascribed  to 
them,  —  a  life  similar  to  that  possessed  by  the  germ 
of  a  seed,  which  enables  it  under  favorable  condi- 
tions to  develop  and  multiply  itself.  It  would  be 
impossible  to  find  a  more  correct  figurative  repre- 
sentation of  these  phenomena;  it  is  one  which  is 
applicable  to  contagions,  as  well  as  to  ferment,  to 
animal  and  vegetable  substances  in  a  state  of  fer- 
mentation, putrefaction  or  decay,  and  even  to  a  piece 
of  decaying  wood,  which  by  mere  contact  with  fresh 
w^ood,  causes  the  latter  to  undergo  gradually  the 
same  change  and  become  decayed  and  mouldered. 

If  the  property  possessed  by  a  body  of  producing 
such  a  change  in  any  other  substance  as  causes  the 
reproduction  of  itself,  with  all  its  properties,  be 
regarded  as  life,  then,  indeed,  all  the  above  phenom- 
ena may  be  ascribed  to  life.  But  in  that  case  they 
must  not  be  considered  as  the  only  processes  due  to 
vitality,  for  the  above  interpretation  of  the  expres- 
sion embraces  the  majority  of  the  phenomena  which 
occur  in  organic  chemistry.  Life  would,  according 
to  that  view,  be  admitted  to  exist  in  every  body  in 
which  chemical  forces  act. 


MORBID  POISONS.  391 

If  a  body  A,  for   example   oxamide  (a  substance 
scarcely  soluble  in  water,  and  without  the  slightest 
taste),  be  brought  into   contact   with   another   com- 
pound B,  which  is   to  be  reproduced;    and  if   this 
second  body  be  oxalic  acid  dissolved  in  water ;  then 
the  following  changes  are  observed  to  take  place:  — 
The    oxamide    is    decomposed   by   the    oxalic    acid, 
provided  the  conditions  necessary  for  their  exercis- 
ing an  action  upon  one   another  are  present.     The 
f    elements   of   water   unite   with   the   constituents   of 
oxamide,  and  ammonia  is  one  product  formed,  and 
j    axalic   acid    the    other,   both  in  exactly  the    proper 
'    proportions  to  combine  and  form  a  neutral  salt. 

Here  the  contact  of  oxamide  and  oxalic  acid  induces 
a  transformation  of  the  oxamide,  which  is  decomposed 
into  oxalic  acid  and  ammonia.  The  oxalic  acid  thus 
formed,  as  well  as  that  originally  added,  are  shared 
by  the  ammonia,  —  or  in  other  words,  as  much  free 
oxalic  acid  exists  after  the  decomposition  as  before 
it,  and  is  of  course  still  possessed  of  its  original 
power.  It  matters  not  whether  the  free  oxalic  acid 
is  that  originally  added,  or  that  newly  produced;  it 
is  certain  that  it  has  been  reproduced  in  an  equal 
quantity  by  the  decomposition. 

If  we  now  add  to  the  same  mixture  a  fresh  portion 
of  oxamide,  exactly  equal  in  quantity  to  that  first 
used,  and  treat  it  in  the  same  manner,  the  same 
decomposition  is  repeated ;  the  free  oxalic  acid  en- 
ters into  combination,  whilst  another  portion  is 
liberated.  In  this  manner  a  very  minute  quantity 
of  oxalic  acid  may  be  made  to  effect  the  decomposi- 
tion of  several  hundred  pounds  of  oxamide ;  and 
one  grain  of  the  acid  to  reproduce  itself  in  unlimited 
quantity. 

We  know  that  the  contact  of  the  virus  of  small- 
pox causes  such  a  change  in  the  blood,  as  gives  rise 
to  the  reproduction  of  the  poison  from  the  constitu- 
ents of  the  fluid.  This  transformation  is  not  arrested 
until  all  the  particles  of  the  blood  which  are  suscep- 
tible of  the  decomposition  have  undergone  the  met- 


392  POISONS,  CONTAGIONS,  MIASMS. 

araorphosis.  We  have  just  seen  that  the  contact  of 
oxalic  acid  with  oxaraide  caused  the  production  of 
fresh  oxalic  acid,  which  in  its  turn  exercised  the 
same  action  on  a  new  portion  of  oxamide.  The 
transformation  was  only  arrested  in  consequence  of 
the  quantity  of  oxamide  present  being  limited.  In 
their  form  both  these  transformations  belong  to  the 
same  class.  But  no  one  except  a  person  quite  unac- 
customed to  view  such  changes  will  ascribe  them  to 
a  vital  power,  although  we  admit  they  correspond 
remarkably  to  our  common  conceptions  of  life ;  they 
are  really  chemical  processes  dependent  upon  the 
common  chemical  forces. 

Our  notion  of  life  involves  something  more  than 
mere  reproduction,  namely,  the  idea  of  an  active 
power  exercised  hy  virtue  of  a  definite  form,  and 
production  and  generation  in  a  definite  form.  By 
chemical  agency  we  can  produce  the  constituents  of 
muscular  fibre,  skin,  and  hair ;  but  we  can  form  by 
their  means  no  organized  tissue,  no  organic  cell. 

The  production  of  organs,  the  cooperation  of  a 
system  of  organs,  and  their  power  not  only  to  pro- 
duce their  component  parts  from  the  food  presented 
to  them,  but  to  generate  themselves  in  their  original 
form  and  with  all  their  properties,  are  characters 
belonging  exclusively  to  organic  life,  and  constitute 
a  form  of  reproduction  independent  of  chemical 
powers. 

The  chemical  forces  are  subject  to  the  invisible 
cause  by  which  this  form  is  produced.  Of  the  exist- 
ence of  this  cause  itself  we  are  made  aware  only  by 
the  phenomena  which  it  produces.  Its  laws  must  be 
investigated  just  as  we  investigate  those  of  the  other 
powers  which  effect  motion  and  changes  in  matter. 

The  chemical  forces  are  subordinate  to  this  cause 
of  life,  just  as  they  are  to  electricity,  heat,  mechan- 
ical motion,  and  friction.  By  the  influence  of  the 
latter  forces,  they  suffer  changes  in  their  direction, 
an  increase  or  diminution  of  their  intensity,  or  a 
complete  cessation  or  reversal  of  their  action. 


THEIR  MODE  OF  ACTION.  393 

Such  an  influence  and  no  other  is  exercised  by  the 
vital  principle  over  the  chemical  forces ;  but  in  every 
case  where  combination  or  decomposition  takes 
place,  chemical  affinity  and  cohesion  are  in  action. 

The  vital  principle  is  only  known  to  us  through 
the  peculiar  form  of  its  instruments,  that  is,  through 
the  organs  in  which  it  resides.  Hence,  whatever 
kind  of  energy  a  substance  may  possess,  if  it  is 
amorphous  and  destitute  of  organs  from  which  the 
impulse,  motion  or  change  proceeds,  it  does  not  live. 
Its  energy  depends  in  this  case  on  a  chemical  action. 
Light,  heat,  electricity,  or  other  influences  may  in- 
crease, diminish,  or  arrest  this  action,  but  they  are 
not  its  efficient  cause. 

In  the  same  way  the  vital  principle  governs  the 
chemical  powers  in  the  living  body.  All  those  sub- 
stances to  which  we  apply  the  general  name  of  food, 
and  all  the  bodies  formed  from  them  in  the  organism, 
are  chemical  compounds.  The  vital  principle  has, 
therefore,  no  other  resistance  to  overcome,  in  order 
to  convert  these  substances  into  component  parts  of 
the  organism,  than  the  chemical  powers  by  which 
their  constituents  are  held  together.  If  the  food  pos- 
sessed life,  not  merely  the  chemical  forces,  but  this 
vitality,  would  offer  resistance  to  the  vital  force  of 
the  organism  it  nourished. 

All  substances  adapted  for  assimilation  are  bodies 
of  a  very  complex  constitution ;  their  atoms  are 
highly  complex,  and  are  held  together  only  by  a 
weak  chemical  action.  They  are  formed  by  the  union 
of  two  or  more  simple  compounds ;  and  in  propor- 
tion as  the  number  of  their  atoms  augments,  their 
disposition  to  enter  into  new  combinations  is  dimin- 
ished ;  that  is,  they  lose  the  power  of  acting  chem- 
ically upon  other  bodies. 

Their  complex  nature,  however,  renders  them 
more  liable  to  be  changed,  by  the  agency  of  external 
causes,  and  thus  to  suffer  decomposition.  Any  ex- 
ternal agency,  in  many  cases  even  mechanical  friction, 
is  sufficient  to  cause  a  disturbance  in  the  equilibrium 


394  POISONS,  CONTAGIONS,  MIASMS. 

of  the  attraction  of  their  constituents ;  they  arrange 
themselves  either  into  new,  more  simple,  and  perma- 
nent combinations,  or  if  a  foreign  attraction  exercise 
its  influence  upon  it,  they  arrange  themselves  in 
accordance  with  that  attraction. 

The  special  characters  of  food,  that  is,  of  substan- 
ces fitted  for  assimilation,  are  absence  of  active 
chemical  properties,  and  the  capability  of  yielding 
to  transformations. 

The  equilibrium  in  the  chemical  attractions  of  the 
constituents  of  the  food  is  disturbed  by  the  vital 
principle,  as  we  know  it  may  be  by  many  other  causes. 
But  the  union  of  its  elements,  so  as  to  produce  new 
combinations  and  forms,  indicates  the  presence  of  a 
peculiar  mode  of  attraction,  and  the  existence  of  a 
power  distinct  from  all  other  powers  of  nature, 
namely,  the  vital  principle. 

All  bodies  of  simple  composition  possess  a  greater 
or  less  disposition  to  form  combinations.  Thus  oxalic 
acid  is  one  of  the  simplest  of  the  organic  acids, 
while  stearic  acid  is  one  of  the  most  complex ;  and 
the  former  is  the  strongest,  the  latter  one  of  the 
weakest,  in  respect  to  active  chemical  character.  By 
virtue  of  this  disposition,  simple  compounds  produce 
changes  in  every  body  which  offers  no  resistance  to 
their  action ;  they  enter  into  combination  and  cause 
decomposition. 

The  vital  principle  opposes  to  the  continual  action 
of  the  atmosphere,  moisture  and  temperature  upon 
the  organism,  a  resistance  which  is,  in  a  certain 
degree,  invincible.  It  is  by  the  constant  neutraliza- 
tion and  renewal  of  these  external  influences  that 
life  and  motion  are  maintained. 

The  greatest  wonder  in  the  living  organism  is  the 
fact,  that  an  unfathomable  wisdom  has  made  the 
cause  of  a  continual  decomposition  or  destruction, 
namely,  the  support  of  the  process  of  respiration, 
to  be  the  means  of  renewing  the  organism,  and  of 
resisting  all  the  other  atmospheric  influences,  such 
as  those  of  moisture  and  changes  of  temperature. 


THEIR  MODE  OF  ACTION.  395 

When  a  chemical  compound  of  simple  constitution 
is  introduced  into  the  stomach,  or  any  other  part  of 
the  organism,  it  must  exercise  a  chemical  action 
upon  all  substances  with  which  it  comes  in  contact ; 
for  we  know  the  peculiar  character  of  such  a  body 
to  be  an  aptitude  and  power  to  enter  into  combina- 
tions and  effect  decompositions. 

The  chemical  action  of  such  a  compound  is  of 
course  opposed  by  the  vital  principle.  The  results 
produced  depend  upon  the  strength  of  their  respec- 
tive actions ;  either  an  equilibrium  of  both  powers  is 
attained,  a  change  being  effected  without  the  de- 
struction of  the  vital  principle,  in  which  case  a  medi- 
dual  effect  is  occasioned;  or  the  acting  body  yields 
to  the  superior  force  of  vitality,  that  is,  it  is  digested  ; 
or  lastly,  the  chemical  action  obtains  the  ascendency 
and  acts  as  a  poison. 

Every  substance  may  be  considered  as  nutriment, 
which  loses  its  former  properties  when  acted  on  by 
the  vital  principle,  and  does  not  exercise  a  chemical 
action  upon  the  living  organ. 

Bodies  of  another  class  change  the  direction,  the 
strength,  and  intensity  of  the  resisting  force  (the 
vital  principle),  and  thus  exert  a  modifying  influence 
upon  the  functions  of  its  organs.  They  produce  a 
disturbance  in  the  system,  either  by  their  presence, 
or  by  themselves  undergoing  a  change ;  these  are 
medicaments. 

Compounds  of  a  third  class  are  called  poisons, 
when  they  possess  the  property  of  uniting  with  or- 
gans or  with  their  component  parts,  and  when  their 
power  of  effecting  this  is  stronger  than  the  resis- 
tance offered  by  the  vital  principle. 

The  quantity  of  a  substance  and  its  condition  must 
obviously  completely  change  the  mode  of  its  chemi- 
cal action. 

Increase  of  quantity  is  known  to  be  equivalent  to 
superior  affinity.  Hence  a  medicament  administered 
in  excessive  quantity  may  act  as  a  poison,  and  a 
poison  in  small  doses  as  a  medicament. 


396  POISONS,  CONTAGIONS,  MIASMS. 

Food  will  act  as  a  poison,  that  is,  it  will  produce 
disease,  when  it  is  able  to  exercise  a  chemical  action 
by  virtue  of  its  quantity;  or,  when  either  its  con- 
dition or  its  presence  retards,  prevents,  or  arrests 
the  motion  of  any  organ. 

A  compound  acts  as  a  poison  when  all  the  parts 
of  an  organ  with  which  it  is  brought  into  contact 
enter  into  chemical  combination  with  it,  while  it  may 
operate  as  a  medicine,  when  it  produces  only  a  par- 
tial change. 

No  other  component  part  of  the  organism  can  be 
compared  to  the  blood,  in  respect  of  the  feeble  re- 
sistance which  it  offers  to  exterior  influences.  The 
blood  is  not  an  organ  which  is  formed,  but  an  organ 
in  the  act  of  formation ;  indeed,  it  is  the  sum  of  all 
the  organs  which  are  being  formed.  The  chemical 
force  and  the  vital  principle  hold  each  other  in  such 
perfect  equilibrium,  that  every  disturbance,  however 
trifling,  or  from  whatever  cause  it  may  proceed,  effects 
a  change  in  the  blood.  This  liquid  possesses  so 
little  of  permanence,  that  it  cannot  be  removed  from 
the  body  without  immediately  suffering  a  change, 
and  cannot  come  in  contact  with  any  organ  in  the 
body,  without  yielding  to  its  attraction. 

The  slightest  action  of  a  chemical  agent  upon  the 
blood  exercises  an  injurious  influence;  even  the  mo- 
mentary contact  with  the  air  in  the  lungs,  although 
effected  through  the  medium  of  cells  and  membranes, 
alters  the  color  and  other  qualities  of  the  blood. 
Every  chemical  action  propagates  itself  through  the 
mass  of  the  blood ;  for  example,  the  active  chemical 
condition  of  the  constituents  of  a  body  undergoing 
decomposition,  fermentation,  putrefaction,  or  decay, 
disturbs  the  equilibrium  between  the  chemical  force 
and  the  vital  principle  in  the  circulating  fluid. 
Numerous  modifications  in  the  composition  and  con- 
dition of  the  compounds  produced  from  the  elements 
of  the  blood,  result  from  the  conflict  of  the  vital 
force  with  the  chemical  aflSnity,  in  their  incessant 
endeavor  to  overcome  one  another. 


THEIR  MODE  OF  ACTION.  397 

All  the  characters  of  the  phenomena  of  contagion 
tend  to  disprove  the  existence  of  life  in  contagious 
matters.  They  without  doubt  exercise  an  influence 
very  similar  to  some  processes  in  the  living  organ- 
ism; but  the  cause  of  this  influence  is  chemical 
action,  which  is  capable  of  being  subdued  by  other 
chemical  actions,  by  opposed  agencies. 

Several  of  the  poisons  generated  in  the  body  by 
disease  lose  all  their  power  when  introduced  into 
the  stomach,  but  others  are  not  thus  destroyed. 

It  is  a  fact  very  decisive  of  their  chemical  nature 
and  mode  of  action,  that  those  poisons  which  are 
neutral  or  alkaline,  such  as  the  poisonous  matter  of 
the  contagious  fever  in  cattle  [typhus  contagiosus 
ruminantium),  or  that  of  the  smallpox,  lose  their 
whole  power  of  contagion  in  the  stomach ;  whilst 
that  of  sausages,  which  has  an  acid  reaction,  retains 
all  its  frightful  properties  under  the  same  circum- 
stances. 

In  the  former  of  these  cases,  the  free  acid  present 
in  the  stomach  destroys  the  action  of  the  poison, 
the  chemical  properties  of  which  are  opposed  to  it ; 
whilst  in  the  latter  it  strengthens,  or  at  all  events 
does  not  offer  any  impediment  to  poisonous  action. 

Microscopical  examination  has  detected  peculiar 
bodies  resembling  the  globules  of  the  blood  in  ma- 
lignant putrefying  pus,  in  the  matter  of  vaccine,  &c. 
The  presence  of  these  bodies  has  given  weight  to 
the  opinion,  that  contagion  proceeds  from  the  de- 
velopment of  a  diseased  organic  life ;  and  these  for- 
mations have  been  regarded  as  the  living  seeds  of 
disease. 

This  view,  which  is  not  adapted  to  discussion,  has 
led  those  philosophers,  who  are  accustomed  to  search 
for  explanations  of  phenomena  in  forms,  to  consider 
the  yeast  produced  by  the  fermentation  of  beer  as 
possessed  of  life.  They  have  imagined  it  to  be  com- 
posed of  animals  or  plants,  which  nourish  themselves 
from  the  sugar  in  which  they  are  placed,  and  at  the 

34 


398  POISONS,  CONTAGIONS,  MIASMS. 

same  time  yield  alcohol  and  carbonic  acid  as  excre- 
mentitious  matters.* 

It  would  perhaps  appear  wonderful  if  bodieS;  pos- 
sessing a  crystalline  structure  and  geometrical  figure, 
were  formed  during  the  processes  of  fermentation 
and  putrefaction  from  the  organic  substances  and 
tissues  of  organs.  We  know,  on  the  contrary,  that 
the  complete  dissolution  into  organic  compounds  is 
preceded  by  a  series  of  transformations,  in  which 
the  organic  structures  gradually  resign  their  forms. 

Blood,  in  a  state  of  decomposition  may  appear  to 
the  eye  unchanged;  and  when  we  recognise  the 
globules  of  blood  in  a  liquid  contagious  matter,  the 
utmost  that  we  can  thence  infer  is,  that  those  glob- 
ules have  taken  no  part  in  the  process  of  decompo- 
sition. All  the  phosphate  of  lime  may  be  removed 
from  bones,  leaving  them  transparent  and  flexible 
like  leather,  without  the  form  of  the  bones  being  in 
the  smallest  degree  lost.  Again,  bones  may  be 
burned  until  they  be  quite  white,  and  consist  merely 
of  a  skeleton  of  phosphate  of  lime,  but  they  will  still 
possess  their  original  form.  In  the  same  way  pro- 
cesses of  decomposition  in  the  blood  may  aflect  in- 
dividual constituents  only  of  that  fluid,  which  will 
become  destroyed  and  disappear,  whilst  its  other 
parts  will  maintain  the  original  form. 

Several  kinds  of  contagion  are  propagated  through 
the  air :  so  that,  according  to  the  view  already 
mentioned,  we  must  ascribe  life  to  a  gas,  that  is,  to 
an  aeriform  body. 

All  the  supposed  proofs  of  the  vitality  of  con- 
tagions are  merely  ideas  and  figurative  representa- 
tions, fitted  to  render  the  phenomena  more  easy  of 
apprehension  by  our  senses,  without  explaining  them 
These  figurative  expressions,  with  which  we  are  so 
willingly  and  easily  satisfied  in  all  sciences,  are  the 
foes  of  all  inquiries  into  the  mysteries  of  nature  ;  they 
are  like  the/a^a  morgana,  which  show  us  deceitful 


*  Annalen  der  Pharmacie,  Band  xxix.  S.  93  und  100. 


THEIR  MODE  OF  ACTION.  399 

views  of  seas,  fertile  fields,  and  luscious  fruits,  but 
leave  us  languishing  when  we  have  most  need  of 
what  they  promise. 

It  is  certain,  that  the  action  of  contagions  is  the 
result  of  a  peculiar  influence  dependent  on  chemical 
forces,  and  in  no  way  connected  with  the  vital  prin- 
ciple. This  influence  is  destroyed  by  chemical  ac- 
tions, and  manifests  itself  wherever  it  is  not  sub- 
dued by  some  antagonist  power.  Its  existence  is 
recognised  in  a  connected  series  of  changes  and 
transformations,  in  which  it  causes  all  substances 
capable  of  undergoing  similar  changes  to  participate. 

An  animal  substance  in  the  act  of  decomposition, 
or  a  substance  generated  from  the  component  parts 
of  a  living  body  by  disease,  communicates  its  own 
condition  to  all  parts  of  the  system  capable  of  enter- 
ing into  the  same  state,  if  no  cause  exist  in  these 
parts  by  which  the  change  is  counteracted  or  de- 
stroyed. 

Disease  is  excited  by  contagion. 

The  transformations  produced  by  the  disease  as- 
sume a  series  of  forms. 

In  order  to  obtain  a  clear  conception  of  these 
transformations,  we  may  consider  the  changes  which 
substances,  more  simply  composed  than  the  living 
body,  suffer  from  the  influence  of  similar  causes. 
When  putrefying  blood  or  yeast  in  the  act  of  trans- 
formation is  placed  in  contact  with  a  solution  of 
sugar,  the  elements  of  the  latter  substance  are  trans- 
posed, so  as  to  form  alcohol  and  carbonic  acid. 

A  piece  of  the  rennet-stomach  of  a  calf  in  a  state 
of  decomposition  occasions  the  elements  of  sugar  to 
assume  a  different  arrangement.  The  sugar  is  con- 
verted into  lactic  acid  without  the  addition  or  loss 
of  any  element.  (1  atom  of  sugar  of  grapes  C12 
H12  012  yields  two  atoms  of  lactic  acid  =2  (C6 
H6  06.) 

When  the  juice  of  onions  or  of  beet-root  is  made 
to  ferment  at  high  temperatures,  lactic  acid,  mannite, 
and  gum  are  formed.     Thus,  according  to  the  differ- 


400  POISONS,  CONTAGIONS,  MIASMS. 

ent  states  of  the  transposition  of  the  elements  of  the 
exciting  body,  the  elements  of  the  sugar  arrange 
themselves  in  different  manners,  that  is,  different 
products  are  formed. 

The  immediate  contact  of  the  decomposing  sub- 
stance with  the  sugar  is  the  cause  by  which  its 
particles  are  made  to  assume  new  forms  and  natures. 
The  removal  of  that  substance  occasions  the  cessa- 
tion of  the  decomposition  of  the  sugar,  so  that, 
should  its  transformation  be  completed  before  the 
sugar,  the  latter  can  suffer  no  further  change. 

In  none  of  these  processes  of  decomposition  is 
the  exciting  body  reproduced ;  for  the  conditions 
necessary  to  its  reproduction  do  not  exist  in  the 
elements  of  the  sugar. 

Just  as  yeast,  putrefying  flesh,  and  the  stomach 
of  a  calf  in  a  state  of  decomposition,  when  intro- 
duced into  solutions  of  sugar,  effect  the  transforma- 
tion of  this  substance,  without  being  themselves  re- 
generated ;  in  the  same  manner,  miasms  and  certain 
contagious  matters  produce  diseases  in  the  human 
organism,  by  communicating  the  state  of  decompo- 
sition, of  which  they  themselves  are  the  subject,  to 
certain  parts  of  the  organism,  without  themselves 
being  reproduced  in  their  peculiar  form  and  nature 
during  the  progress  of  the  decomposition. 

The  disease  in  this  case  is  not  contagious. 

Now  when  yeast  is  introduced  into  a  mixed  liquid 
containing  both  sugar  and  gluten,  such  as  wort,  the 
act  of  decomposition  of  the  sugar  effects  a  change 
in  the  form  and  nature  of  the  gluten,  which  is,  in 
consequence,  also  subjected  to  transformation.  As 
long  as  some  of  the  fermenting  sugar  remains,  gluten 
continues  to  be  separated  as  yeast,  and  this  new 
matter  in  its  turn  excites  fermentation  in  a  fresh 
solution  of  sugar  or  wort.  If  the  sugar,  however, 
should  be  first  decomposed,  the  gluten  which  re- 
mains in  solution  is  not  converted  into  yeast.  We 
see,  therefore,  that  the  reproduction  of  the  exciting 
body  here  depends, — 


THEIR  MODE  OF  ACTION.  401 

1.  Upon  the  presence  of  that  substance  from  which 
it  was  originally  formed ; 

2.  Upon  the  presence  of  a  compound  w^hich  is 
capable  of  being   decomposed  by  contact  with   the 

Exciting  body. 

If  we  express  in  the  same  terms  the  reproduction 
of  contagious  matter  in  contagious  diseases,  since  it 
is  quite  certain  that  they  must  have  their  origin  in 
the  blood,  we  must  admit  that  the  blood  of  a  healthy 
individual  contains  substances,  by  the  decomposition 
of  which  the  exciting  body  or  contagion  can  be  pro- 
duced. It  must  further  be  admitted,  when  contagion 
results,  that  the  blood  contains  a  second  constituent 
capable  of  being  decomposed  by  the  exciting  body. 
It  is  only  in  consequence  of  the  conversion  of  the 
second  constituent,  that  the  original  exciting  body 
can  be  reproduced. 

A  susceptibility  of  contagion  indicates  the  pres- 
ence of  a  certain  quantity  of  this  second  body  in  the 
blood  of  a  healthy  individual.  The  susceptibility 
for  the  disease  and  its  intensity  must  augment  ac- 
cording to  the  quantity  of  that  body  present  in  the 
blood;  and  in  proportion  to  its  diminution  or  dis- 
appearance, the  course  of  the  disease  will  change. 

When  a  quantity,  however  small,  of  contagious 
matter,  that  is,  of  the  exciting  body,  is  introduced 
into  the  blood  of  a  healthy  individual,  it  will  be 
again  generated  in  the  blood,  just  as  yeast  is  repro- 
duced from  wort.  Its  condition  of  transformation 
will  be  communicated  to  a  constituent  of  the  blood; 
and  in  consequence  of  the  transformation  suffered  by 
this  substance,  a  body  identical  with  or  similar  to 
the  exciting  or  contagious  matter  will  be  produced 
from  another  constituent  substance  of  the  blood. 
The  quantity  of  the  exciting  body  newly  produced 
must  constantly  augment,  if  its  further  transforma- 
tion or  decomposition  proceeds  more  slowly  than 
that  of  the  compound  in  the  blood,  the  decompo- 
sition of  which  it  effects. 

If  the   transformation   of  the  yeast  generated  in 


402  POISONS,  CONTAGIONS,  MIASMS. 

the  fermentation  of  wort  proceeded  with  the  same 
rapidity  as  that  of  the  particles  of  the  sugar  con- 
tained in  it,  both  would  simultaneously  disappear 
when  the  fermentation  was  completed.  But  yeast 
requires  a  much  longer  time  for  decomposition  than 
sugar,  so  that  after  the  latter  has  completely  disap- 
peared, there  remains  a  much  larger  quantity  of 
yeast  than  existed  in  the  fluid  at  the  commencement 
of  the  fermentation,  —  yeast  which  is  still  in  a  state 
of  incessant  progressive  transformation,  and  there- 
fore possessed  of  its  peculiar  property. 

The  state  of  change  or  decomposition  which  effects 
one  particle  of  blood,  is  imparted  to  a  second,  a 
third,  and  at  last  to  all  the  particles  of  blood  in  the 
whole  body.  It  is  communicated  in  like  manner  to 
the  blood  of  another  individual,  to  that  of  a  third 
person,  and  so  on,  —  or  in  other  words,  the  disease 
is  excited  in  them  also. 

It  is  quite  certain,  that  a  number  of  peculiar  sub- 
stances exist  in  the  blood  of  some  men  and  animals, 
which  are  absent  from  the  blood  of  others. 

The  blood  of  the  same  individual  contains,  in 
childhood  and  youth,  variable  quantities  of  substan- 
ces, which  are  absent  from  it  in  other  stages  of 
growth.  The  susceptibility  of  contagion  by  peculiar 
exciting  bodies  in  childhood,  indicates  a  propagation 
and  regeneration  of  the  exciting  bodies,  in  conse- 
quence of  the  transformation  of  certain  substances 
which  are  present  in  the  blood,  and  in  the  absence 
of  which  no  contagion  could  ensue.  The  form  of  a 
disease  is  termed  benignant,  when  the  transforma- 
tions are  perfected  on  constituents  of  the  body  which 
are  not  essential  to  life,  without  the  other  parts 
taking  a  share  in  the  decomposition;  it  is  termed 
malignant  when  they  affect  essential  organs. 

It  cannot  be  supposed,  that  the  different  changes 
in  the  blood,  by  which  its  constituents  are  converted 
into  fat,  muscular  fibre,  substance  of  the  brain  and 
nerves,  bones,  hair,  &c.,  and  the  transformation  of 
.food  into  blood,  can  take  place  without  the  simulta- 


THEIR  MODE  OF  ACTION.  403 

neous  formation  of  new  compounds  which  require  to 
be  removed  from  the  body  by  the  organs  of  excre- 
tion. 

In  an  adult  these  excretions  do  not  vary  much 
either  in  their  nature  or  quantity.  The  food  taken 
is  not  employed  in  increasing  the  size  of  the  body, 
but  merely  for  the  purpose  of  replacing  any  sub- 
stances which  may  be  consumed  by  the  various 
actions  in  the  organism;  every  motion,  every  mani- 
festation of  organic  properties,  and  every  organic 
action  being  attended  by  a  change  in  the  material 
of  the  body,  and  by  the  assumption  of  a  new  form 
by  its  constituents.* 

But  in  a  child  this  normal  condition  of  sustenance 
is  accompanied  by  an  abnormal  condition  of  growth 
and  increase  in  the  size  of  the  body,  and  of  each 
individual  part  of  it.  Hence  there  must  be  a  much 
larger  quantity  of  foreign  substances,  not  belonging 
to  the  organism,  diffused  through  every  part  of  the 
blood  in  the  body  of  a  young  individual. 

When  the  organs  of  secretion  are  in  proper  action, 
these  substances  will  be  removed  from  the  system; 
but  when  the  functions  of  those  organs  are  impeded, 
they  will  remain  in  the  blood  or  become  accumulated 
in  particular  parts  of  the  body.  The  skin,  lungs, 
and  other  organs,  assume  the  functions  of  the  dis- 
eased secreting  organs,  and  the  accumulated  sub- 
stances are  eliminated  by  them.  If,  when  thus 
exhaled,  these  substances  happen  to  be  in  the  state 
of  progressive  transformation,  they  are  contagious ; 
that  is,  they  are  able  to  produce  the  same  state  of 
disease  in  another  healthy  organism,  provided  the 
latter  organism  is  susceptible  of  their  action,  —  or 
in  other  words,  contains  a  matter  capable  of  suffer- 
ing the  same  process  of  decomposition. 

*  The  experiments  of  Barruel  upon  the  different  odors  emitted  from 
blood  on  the  addition  of  sulphuric  acid,  prove  that  peculiar  substances 
are  contained  in  the  blood  of  different  individuals;  the  blood  of  a  man 
of  a  fair  complexion  and  that  of  a  man  of  dark  complexion  were  found 
to  yield  different  odors ;  the  blood  of  animals  also  differed  in  this  respect 
very  perceptibly  from  that  of  man. — L. 


404  POISONS,  CONTAGIONS,  MIASMS. 

The  production  of  matters  of  this  kind,  which 
render  the  body  susceptible  of  contagion,  may  be 
occasioned  by  the  manner  of  living,  or  by  the  nutri- 
ment taken  by  an  individual.  A  superabundance  of 
strong  and  otherwise  wholesome  food  may  produce 
them,  as  well  as  a  deficiency  of  nutriment,  unclean- 
liness,  or  even  the  use  of  decayed  substances  as 
food. 

All  these  conditions  for  contagion  must  be  con- 
sidered as  accidental.  Their  formation  and  accu- 
mulation in  the  body  may  be  prevented,  and  they 
may  even  be  removed  from  it  without  disturbing  its 
most  important  functions  or  health.  Their  presence 
is  not  necessary  to  life. 

The  action,  as  well  as  the  generation  of  the  matter 
of  contagion  is,  according  to  this  view,  a  chemical 
process  participated  in  by  all  substances  in  the 
living  body,  and  by  all  the  constituents  of  those 
organs  in  which  the  vital  principle  does  not  over- 
come the  chemical  action.  The  contagion,  accord- 
ingly, either  spreads  itself  over  every  part  of  the 
body,  or  is  confined  particularly  to  certain  organs, 
that  is,  the  disease  attacks  all  the  organs  or  only  a 
few  of  them,  according  to  the  feebleness  or  intensity 
of  their  resistance. 

In  the  abstract  chemical  sense,  reproduction  of  a 
contagion  depends  upon  the  presence  of  two  sub- 
stances, one  of  which  becomes  completely  decom- 
posed, but  communicates  its  own  state  of  transform- 
ation to  the  second.  The  second  substance  thus 
thrown  into  a  state  of  decomposition  is  the  newly- 
formed  contagion. 

The  second  substance  must  have  been  originally  a 
constituent  of  the  blood :  the  first  may  be  a  body 
accidentally  present;  but  it  may  also  be  a  matter 
necessary  to  life.  If  both  be  constituents  indispen- 
sable for  the  support  of  the  vital  functions  of  certain 
principal  organs,  death  is  the  consequence  of  their 
transformation.  But  if  the  absence  of  the  one  sub- 
stance  which  was  a  constituent  of  the  blood  do  not 


THEIR  MODE  OF  ACTION.  405 

cause  an  immediate  cessation  of  the  functions  of 
the  most  important  organs,  if  they  continue  in  their 
action,  although  in  an  abnormal  condition,  conval- 
escence ensues.  In  this  case  the  products  of  the 
transformations  still  existing  in  the  blood  are  used 
for  assimilation,  and  at  this  period  secretions  of  a 
peculiar  nature  are  produced. 

When  the  constituent  removed  from  the  blood  is 
a  product  of  an  unnatural  manner  of  living,  or  when 
its  formation  takes  place  only  at  a  certain  age,  the 
susceptibility  of  contagion  ceases  upon  its  disap- 
pearance. 

The  effects  of  vaccine  matter  indicate,  that  an 
accidental  constituent  of  the  blood  is  destroyed  by 
a  peculiar  process  of  decomposition,  which  does  not 
affect  the  other  constituents  of  the  circulating  fluid. 

If  the  manner  in  which  the  precipitated  yeast  of 
Bavarian  beer  acts  (page  350)  be  called  to  mind, 
the  modus  operandi  of  vaccine  lymph  can  scarcely 
be  matter  of  doubt. 

Both  the  kind  of  yeast  here  referred  to  and  the 
ordinary  ferment  are  formed  from  gluten,  just  as  the 
vaccine  virus  and  the  matter  of  smallpox  are  pro- 
duced from  the  blood.  Ordinary  yeast  and  the  virus 
of  human  smallpox,  however,  effect  a  violent  tumul- 
tuous transformation,  the  former  in  vegetable  juices, 
the  latter  in  blood,  in  both  of  which  fluids  respec- 
tively their  constituents  are  contained,  and  they  are 
reproduced  from  these  fluids  with  all  their  character- 
istic properties.  The  precipitated  yeast  of  Bavarian 
beer  on  the  other  hand  acts  entirely  upon  the  sugar 
of  the  fermenting  liquid  and  occasions  a  very  pro- 
tracted decomposition  of  it,  in  which  the  gluten 
which  is  also  present  takes  no  part.  But  the  air 
exercises  an  influence  upon  the  latter  substance,  and 
causes  it  to  assume  a  new  form  and  nature,  in  con- 
sequence of  which  this  kind  of  yeast  also  is  repro- 
duced. 

The  action  of  the  virus  of  cow-pox  is  analogous 
to  that  of  the  low   yeast ;  it  communicates  its   own 


406  POISONS,  CONTAGIONS,  MIASMS. 

state  of  decomposition  to  a  matter  in  the  blood,  and 
from  a  second  matter  is  itself  regenerated,  but  by  a 
totally  different  mode  of  decomposition;  the  product 
possesses  the  mild  form,  and  all  the  properties  of 
the  lymph  of  cow-pox. 

The  susceptibility  of  infection  by  the  virus  of 
human  smallpox  must  cease  after  vaccination,  for 
the  substance  to  the  presence  of  which  this  suscep- 
tibility is  owing  has  been  removed  from  the  body  by 
a  peculiar  process  of  decomposition  artificially  ex- 
cited. But  this  substance  may  be  again  generated 
in  the  same  individual,  so  that  he  may  again  become 
liable  to  contagion,  and  a  second  or  a  third  vaccina- 
tion will  again  remove  the  peculiar  substance  from 
the  system. 

Chemical  actions  are  propagated  in  no  organs  so 
easily  as  in  the  lungs,  and  it  is  well  known  that  dis- 
eases of  the  lungs  are  above  all  others  frequent  and 
dangerous. 

If  it  is  assumed,  that  chemical  action  and  the  vital 
principle  mutually  balance  each  other  in  the  blood,  it 
must  further  be  supposed  that  the  chemical  powers 
will  have  a  certain  degree  of  preponderance  in  the 
lungs,  where  the  air  and  blood  are  in  immediate 
contact;  for  these  organs  are  fitted  by  nature  to 
favor  chemical  action;  they  offer  no  resistance  to  the 
changes  experienced  by  the  venous  blood. 

The  contact  of  air  with  venous  blood  is  limited  to 
a  very  short  period  of  time  by  the  motion  of  the 
heart,  and  any  change  beyond  a  determinate  point 
is,  in  a  certain  degree,  prevented  by  the  rapid  re- 
moval of  the  blood  which  has  become  arterialized. 
Any  disturbance  in  the  functions  of  the  heart,  and 
any  chemical  action  from  without,  even  though  weak, 
occasions  a  change  in  the  process  of  respiration. 
Solid  substances,  also,  such  as  dust  from  vegetable, 
animal,  or  inorganic  bodies,  act  in  the  same  way  as 
they  do  in  a  saturated  solution  of  a  salt  in  the  act 
of  crystallization,  that  is,  they  occasion  a  deposition 


THEIR  MODE  OF  ACTION.  *  407 

of  solid  matters  from  the  blood,  by  which  the  action 
of  the  air  upon  the  latter  is  altered  or  prevented. 
""When  gaseous  and  decomposing  substances,  or 
those  which  exercise  a  chemical  action,  such  as  sul- 
phuretted hydrogen  and  carbonic  acid,  obtain  access 
to  the  lungs,  they  meet  with  less  resistance  in  this 
organ  than  in  any  other.  The  chemical  process  of 
slow  combustion  in  the  lungs  is  accelerated  by  all 
substances  in  a  state  of  decay  or  putrefaction,  by 
ammonia  and  alkalies^  but  it  is  retarded  by  empy- 
reumatic  substances,  volatile  oils,  and  acids.  Sulphu- 
retted hydrogen  produces  immediate  decomposition 
of  the  blood,  and  sulphurous  acid  combines  with  the 
substance  of  the  tissues,  the  cells,  and  membranes. 

When  the  process  of  respiration  is  modified  by 
contact  with  a  matter  in  the  progress  of  decay,  when 
this  matter  communicates  the  state  of  decomposition, 
of  which  it  is  the  subject,  to  the  blood,  disease  is 
produced. 

If  the  matter  undergoing  decomposition  is  the 
product  of  a  disease,  it  is  called  contagion;  but  if 
it  is  a  product  of  the  decay  or  putrefaction  of  ani- 
mal and  vegetable  substances,  or  if  it  acts  by  its 
chemical  properties,  (not  by  the  state  in  w^hich  it  is,) 
and  therefore  enters  into  combination  with  parts  of 
the  body,  or  causes  their  decomposition,  it  is  termed 
miasm. 

Gaseous  contagious  matter  is  a  miasm  emitted 
from  blood,  and  capable  of  generating  itself  again  in 
blood. 

But  miasm  properly  so  called,  causes  disease  with- 
out being  itself  reproduced. 

All  the  observations  hitherto  made  upon  gaseous 
contagious  matters  prove,  that  they  also  are  sub- 
stances in  a  state  of  decomposition.  When  vessels 
filled  with  ice  are  placed  in  air  impregnated  with 
gaseous  contagious  matter,  their  outer  surfaces  be- 
come covered  with  water  containing  a  certain  quan- 
tity of  this  matter  in  solution.  This  water  soon 
becomes  turbid,  and  in  common  language  putrefies. 


408  POISONS,  CONTAGIONS,  MIASMS. 

or,  to  describe  the  change  more  correctly,  the  state 
.  of  decomposition  of  the  dissolved  contagious  matter 
is  completed  in  the  water. 

All  gases  emitted  from  putrefying  animal  and 
vegetable  substances  in  processes  of  disease,  gener- 
ally possess  a  peculiar  nauseous  offensive  smell,  a 
circumstance  which,  in  most  cases,  proves  the  pres- 
ence of  a  body  in  a  state  of  decomposition.  Smell 
itself  may  in  many  cases  be  considered  as  a  reaction 
of  the  nerves  of  smell,  or  as  a  resistance  offered  by 
the  vital  powers  to  chemical  action. 

Many  metals  emit  a  peculiar  odor  when  rubbed, 
but  this  is  the  case  with  none  of  the  precious  metals, 
—  those  which  suffer  no  change  when  exposed  to  air 
and  moisture.  Arsenic,  phosphorus,  musk,  the  oils 
of  linseed,  lemons,  turpentine,  rue,  and  peppermint, 
possess  an  odor  only  when  they  are  in  the  act  of 
eremacausis  (oxidation  at  common  temperatures). 

The  odor  of  gaseous  contagious  matters  is  owing 
to  the  same  cause;  but  it  is  also  generally  accom- 
panied by  ammonia,  which  may  be  considered  in 
many  cases  as  the  means  through  which  the  con- 
tagious matter  receives  a  gaseous  form,  just  as  it  is 
the  means  of  causing  the  smell  of  innumerable  sub- 
stances of  little  volatility,  and  of  many  which  have 
no  odor.     (Robiquet.)* 

Ammonia  is  very  generally  produced  in  cases  of 
disease ;  it  is  always  emitted  in  those  in  which  con- 
tagion is  generated,  and  is  an  invariable  product  of 
the  decomposition  of  animal  matter.  The  presence 
of  ammonia  in  the  air  of  chambers  in  which  diseased 
patients  lie,  particularly  of  those  afflicted  with  a 
contagious  disease,  may  be  readily  detected  ;  for  the 
moisture  condensed  by  ice  in  the  manner  just  de- 
scribed, produces  a  white  precipitate  in  a  solution 
of  corrosive  sublimate,  just  as  a  solution  of  ammonia 
does.  The  ammoniacal  salts  also,  which  are  obtained 
by  the  evaporation  of  rain  water  after  an  acid  has 

*  Ann.  de  Chira.  et  de  Phys.  XV.  27. 


their' MODE  OF  ACTION.  409 

been  added,  when  treated  with  lime  so  as  to  set  free 
their  ammonia,  emit  an  odor  most  closely  resembling 
that  of  corpses,  or  the  peculiar  smell  of  dunghills. 

By  evaporating  acids  in  air  containing  gaseous 
contagions,  the  ammonia  is  neutralized,  and  we  thus 
prevent  further  decomposition,  and  destroy  the  pow,- 
er  of  the  contagion,  that  is,  its  state  of  chemical 
change.  Muriatic  and  acetic  acids,  and  in  several 
cases  nitric  acid,  are  to  be  preferred  for  this  purpose 
before  all  others.  Chlorine  also  is  a  substance  which 
destroys  ammonia  and  organic  bodies  with  much 
facility;  but  it  exerts  such  an  injurious  and  prejudi- 
cial influence  upon  the  lungs,  that  it  may  be  classed 
amongst  the  most  poisonous  bodies  known,  and 
should  never  be  employed  in  places  in  which  men 
breathe. 

Carbonic  acid  and  sulphuretted  hydrogen,  which 
are  frequently  evolved  from  the  earth  in  cellars, 
mines,  wells,  sewers,  and  other  places,  are  amongst 
the  most  pernicious  miasms.  The  former  may  be  re- 
moved from  the  air  by  alkalies ;  the  latter,  by  burn- 
ing sulphur  (sulphurous  acid),  or  by  the  evaporation 
of  nitric  acid. 

The  characters  of  many  organic  compounds  are 
well  worthy  of  the  attention  and  study  both  of  phys- 
iologists and  pathologists,  more  especially  in  relation 
to  the  mode  of  action  of  medicines  and  poisons. 

Several  of  such  compounds  are  known,  which  to 
all  appearance  are  quite  indiff*erent  substances,  and 
yet  cannot  be  brought  into  contact  with  one  another 
in  water  without  suffering  a  complete  transformation. 
All  substances  which  thus  suffer  a  mutual  decompo- 
sition, possess  complex  atoms  ;  they  belong  to  the 
highest  order  of  chemical  compounds.  For  example, 
amygdalin,  a  constituent  of  bitter  almonds,  is  a  per- 
fectly neutral  body,  of  a  slightly  bitter  taste,  and 
very  easily  soluble  in  water.  But  when  it  is  intro- 
duced into  a  watery  solution  of  synaptas,  (a  constit- 
uent of  sweet  almonds,)  it  disappears  completely 
without  the  disengagement  of  any  gas,  and  the  wa- 

35 


410  POISONS,   CONTAGIONS,  MIASMS. 

ter  IS  found  to  contain  free  hydrocyanic  acid,  hydru- 
ret  of  benzule  (oil  of  bitter  almonds),  a  peculiar  acid 
and  sugar,  all  substances  of  which  merely  the  ele- 
ments existed  in  the  amygdalin.  The  same  decom- 
position is  effected  when  bitter  almonds,  which  con- 
Jain  the  same  white  matter  as  the  sweet,  are  rubbed 
into  a  powder  and  moistened  with  water.  Hence  it 
happens  that  bitter  almonds  pounded  and  digested 
in  alcohol,  yield  no  oil  of  bitter  almonds  containing 
hydrocyanic  acid,  by  distillation  with  water ;  for  the 
substance  which  occasions  the  formation  of  those 
volatile  substances,  is  dissolved  by  alcohol  without 
change,  and  is  therefore  extracted  from  the  pounded 
almonds.  Pounded  bitter  almonds  contain  no  amyg- 
dalin, also,  after  having  been  moistened  with  water, 
for  that  substance  is  completely  decomposed  when 
they  are  thus  treated. 

No  volatile  compounds  can  be  detected  by  their 
smell  in  the  seeds  of  the  Sinapis  alba  and  S.  nigra. 
A  fixed  oil  of  a  mild  taste  is  obtained  from  them  by 
pressure,  but  no  trace  of  a  volatile  substance.  If, 
however,  the  seeds  are  rubbed  to  a  fine  powder,  and 
subjected  to  distillation  with  water,  a  volatile  oil  of 
a  very  pungent  taste  and  smell  passes  over  along 
with  the  steam.  But  if,  on  the  contrary,  the  seeds 
are  treated  with  alcohol  previously  to  their  distilla- 
tion with  water,  the  residue  does  not  yield  a  volatile 
oil.  The  alcohol  contains  a  crystalline  body  called 
sinapin,  and  several  other  bodies.  These  do  not 
possess  the  characteristic  pungency  of  the  oil,  but  it 
is  by  the  contact  of  them  with  water,  and  with  the 
albuminous  constituents  of  the  seeds,  that  the  vola- 
tile oil  is  formed. 

Thus  bodies  regarded  as  absolutely  indifferent  in 
inorganic  chemistry,  on  account  of  their  possessing 
no  prominent  chemical  characters,  when  placed  in 
contact  with  one  another,  mutually  decompose  each 
other.  Their  constituents  arrange  themselves  in  a 
peculiar  manner,  so  as  to  form  new  combinations ;  a 
complex  atom  dividing   into   two  or  more  atoms  of 


THEIR  MODE  OF  ACTION.  411 

less  complex  constitution,  in  consequence  of  a  mere 
disturbance  in  the  attraction  of  their  elements. 

The  white  constituents  of  the  almonds  and  mus- 
tard which  resemble  coagulated  albumen,  must  be  in 
a  peculiar  state  in  order  to  exert  their  action  upon 
amygdalin,  and  upon  those  constituents  of  mustard 
from  which  the  volatile  pungent  oil  is  produced.  If 
almonds,  after  being  blanched  and  pounded,  are 
thrown  into  boiling  water,  or  treated  with  hot  alco- 
hol, with  mineral  acids,  or  with  salts  of  mercury, 
their  power  to  effect  a  decomposition  in  amygdalin 
is  completely  destroyed.  Synaptas  is  an  azotized 
body  which  cannot  be  preserved  when  dissolved  in 
water.  Its  solution  becomes  rapidly  turbid,  deposits 
a  white  precipitate,  and  acquires  the  offensive  smell 
of  putrefying  bodies. 

It  is  exceedingly  probable,  that  the  peculiar  state 
of  transposition  into  which  the  elements  of  synaptas 
are  thrown  when  dissolved  in  water,  may  be  the 
cause  of  the  decomposition  of  amygdalin,  and  forma- 
tion of  the  new  products  arising  from  it.  The  action 
of  synaptas  in  this  respect  is  very  similar  to  that  of 
rennet  upon  sugar. 

Malt,  and  the  germinating  seeds  of  corn  in  gener- 
al, contain  a  substance  called  diastase^  which  is 
formed  from  the  gluten  contained  in  them,  and  can- 
not be  brought  in  contact  with  starch  and  water, 
without  effecting  a  change  in  the  starch. 

When  bruised  malt  is  strewed  upon  warm  starch, 
made  into  a  paste  with  water,  the  paste  after  a  few 
minutes  becomes  quite  liquid,  and  the  water  is  found 
to  contain,  in  place  of  starch,  a  substance  in  many 
respects  similar  to  gum.  But  when  more  malt  is 
added  and  the  heat  longer  continued,  the  liquid  ac- 
quires a  sweet  taste,  and  all  the  starch  is  found  to 
be  converted  into  sugar  of  grapes. 

The  elements  of  diastase  have  at  the  same  time 
arranged  themselves  into  new  combinations. 

The  conversion  of  the  starch  contained  in  food  in- 
to sugar  of  grapes  in  diabetes  indicates,  that  amongst 


412  POISONS,  CONTAGIONS,  MIASMS. 

the  constituents  of  some  one  organ  of  the  body,  a 
substance  or  substances  exist  in  a  state  of  chemical 
action,  to  which  the  vital  principle  of  the  diseased 
organ  opposes  no  resistance.  The  component  parts 
of  the  organ  must  suffer  changes  simultaneously  with 
the  starch,  so  that  the  more  starch  is  furnished  to  it, 
the  more  energetic  and  intense  the  disease  must 
become ;  while  if  only  food  which  is  incapable  of 
suffering  such  transformations  from  the  same  cause 
is  supplied,  and  the  vital  energy  is  strengthened  by 
stimulant  remedies  and  strong  nourishment,  the 
chemical  action  may  finally  be  subdued,  or  in  other 
words,  the  disease  cured. 

The  conversion  of  starch  into  sugar  may  also  be 
effected  by  pure  gluten,  and  by  dilute  mineral  acids. 

From  all  the  preceding  facts,  we  see  that  very  va- 
rious transpositions,  and  changes  of  composition  and 
properties,  may  be  produced  in  complex  organic 
molecules,  by  every  cause  which  occasions  a  disturb- 
ance in  the  attraction  of  their  elements. 

When  moist  copper  is  exposed  to  air  containing 
carbonic  acid,  the  contact  of  this  acid  increases  the 
affinity  of  the  metal  for  the  oxygen  of  the  air  in  so 
great  a  degree  that  they  combine,  and  the  surface  of 
the  copper  becomes  covered  with  green  carbonate 
of  copper.  Two  bodies,  which  possess  the  power 
of  combining  together,  assume,  however,  opposite 
electric  conditions  at  the  moment  at  which  they  come 
in  contact. 

When  copper  is  placed  in  contact  with  iron,  a  pe- 
culiar electric  condition  is  excited,  in  consequence 
of  which  the  property  of  the  copper  to  unite  with 
oxygen  is  destroyed,  and  the  metal  remains  quite 
bright. 

When  formate  of  ammonia  is  exposed  to  a  temper- 
ature of  388°  F.  (180^  C.)  the  intensity  and  direction 
of  the  chemical  force  undergo  a  change,  and  the 
conditions  under  which  the  elements  of  this  com- 
pound are  enabled  to  remain  in  the  same  form  cease 
to    be    present.      The    elements,   therefore,    arrange 


THEIR  MODE  OF  ACTION.  413 

themselves   in  a  new  form ;    hydrocyanic   acid   and 
water  being  the  results  of  the  change. 

Mechanical  motion,  friction,  or  agitation,  is  suffi- 
cient to  cause  a  new  disposition  of  the  constituents 
of  fulminating  silver  and  mercury,  that  is,  to  effect 
another  arrangement  of  their  elements,  in  conse- 
quence of  which,  new  compounds  are  formed. 

We  know  that  electricity  and  heat  possess  a  de- 
cided influence  upon  the  exercise  of  chemical  affinity ; 
and  that  the  attractions  of  substances  for  one  anoth- 
er are  subordinate  to  numerous  causes  which  change 
the  condition  of  these  substances,  by  altering  the 
direction  of  their  attractions.  In  the  same  manner, 
therefore,  the  exercise  of  chemical  ipowers  in  the 
living  organism  is  dependent  upon  the  vital  principle. 

The  power  of  elements  to  unite  together,  and  to 
form  peculiar  compounds,  which  are  generated  in  an- 
imals and  vegetables,  is  chemical  affinity  |  but  the 
cause  by  which  they  are  prevented  from  arranging 
themselves  according  to  the  degrees  of  their  natural 
attractions,  —  the  cause,  therefore,  by  which  they  are 
made  to  assume  their  peculiar  order  and  form  in  the 
body,  —  is  the  vital  principle. 

After  the  removal  of  the  cause  which  forced  their 
union, —  that  is,  after  the  extinction  of  life,  —  most 
organic  atoms  retain  their  condition,  form,  and  na- 
ture, only  by  a  vis  inerticB  ;  for  a  great  law  of  nature 
proves,  that  matter  does  not  possess  the  power  of 
spontaneous  action.  A  body  in  motion  loses  its  mo- 
tion only  when  a  resistance  is  opposed  to  it;  and  a 
body  at  rest  cannot  be  put  in  motion,  or  into  any 
action  whatever,  without  the  operation  of  some  ex- 
terior cause. 

The  same  numerous  causes  which  are  opposed  to 
the  formation  of  complex  organic  molecules,  under 
ordinary  circumstances,  occasion  their  decomposition 
and  transformations  when  the  only  antagonist  power, 
the  vital  principle,  no  longer  counteracts  the  influ- 
ence of  those  causes.  Contact  with  air  and  the  most 
feeble  chemical  action  now  effect  changes  in  the  com- 

35* 


414  POISONS,  CONTAGIONS,  MIASMS. 

plex  molecules ;  even  the  presence  of  any  body  the 
particles  of  which  are  undergoing  motion  or  trans- 
position, is  often  sufficient  to  destroy  their  state  of 
rest,  and  to  disturb  the  statical  equilibrium  in  the 
attractions  of  their  constituent  elements.  An  imme- 
diate consequence  of  this  is,  that  they  arrange  them- 
selves according  to  the  different  degrees  of  their 
mutual  attractions,  and  that  new  compounds  are 
formed  in  which  chemical  affinity  has  the  ascendancy, 
and  opposes  any  further  change,  while  the  conditions 
under  which  these  compounds  were  formed  remain 
unaltered. 


i 


APPENDIX  TO  PART  II. 


ANTIDOTE    TO    ARSENIC. 

The  following  is  from  a  letter  of  Samuel  L.  Dana,  M.  D., 
of  Lowell,  to  Dr.  Bartlett,  published  in  the  **  Boston  Daily 
Advertiser."     August  3d,  1842. 

**  According  to  the  experiments  of  M.  Guibourt,  white  ox- 
ide of  arsenic,  (or  white  arsenic)  digested  with  hydrated 
peroxide  of  iron,  forms  a  compound,  whose  proportions 
differ  from  that  of  arsenite  of  iron,  by  containing  a  larger 
portion  of'iron.  It  is  this  salt,  which  forms  in  the  stomach, 
when  peroxide  of  iron  is  administered  as  an  antidote  to 
arsenic.  It  contains  3|  times  as  much  iron  as  arsenic.  It 
is  perfectly  insoluble  and  innocuous.  Three  things  are 
essential  to  the  action  of  this  antidote. 

**  1st.  Perfect  freedom  from  protoxide  of  iron. 

**2d.  Perfect  freedom  from  free  alkali,  or  alkali  com- 
bined with  the  oxide  of  iron. 

**3d.   It  must  be  freshly  prepared  without  drying. 

"  1st.  If  the  antidote  contains  protoxide  of  iron,  then 
that  combines  with  the  arsenic  and  forms  a  compound 
which,  though  of  sparing  solubility,  is  yet  poisonous  and 
prevents  the  ulterior  good  action  of  the  peroxide  of  iron. 
A  mixture  of  prot  and  peroxides  of  iron  is  no  antidote  to 
arsenic. 

**  2d.  If  carbonate  of  potash  is  used  to  precipitate  a  solu- 
tion of  persalt  of  iron,  a  portion  falls,  combined  with  alka- 
li. Hence  Berzelius  recommends  bicarbonate  of  potash, 
cold,  to  be  used  for  this  purpose.  The  effect  of  alkali, 
free,  or  thus  combined  with  peroxide  of  iron,  will  be,  to 
form  soluble  poisonous  arsenites  as  above  noticed. 

**3d.  The  effect  depends  on  the  antidote  being  freshly- 
prepared.  I  would  therefore,  in  order  to  insure  the  2d 
and  3d  conditions,  recommend  the  solution  of  pernitrate  of 
iron  to  be  taken  dilute,  followed  by  aq.  am.  and  wet  by  a 


416 


TABLES. 


little  vinegar  or  tartaric  acid,  or  cream  of  tartar ;  remedies 
always  at  hand. 

**To  insure  perfect  freedom  from  protoxide  of  iron, 
I  would  always  pass  a  current  of  chlorine,  through  the 
solution  of  prepared  nitrate  of  iron,  before  that  is  con- 
sidered as  fit,  to  be  kept  on  hand,  for  the  ready  formation 
of  hydrated  peroxide  of  iron. 


TABLES: 


SHOWING   THE    PROPORTION   BETWEEN   THE    HESSIAN   AND 
ENGLISH    STANDARD    OF   WEIGHTS   AND   MEASURES. 


In  general  all  the  weights  and  measures  employed  in  this 
edition  are  those  of  the  English  standard.  In  a  few  cases 
only,  the  Hessian  weights  and  measures  have  been  re- 
tained. In  these  the  numbers  do  not  represent  absolute 
quantites,  but  are  merely  intended  to  denote  a  proportion 
to  other  numbers.  This  has  been  done  to  avoid  any  un- 
necessary intricacy  in  the  calculations,  and  to  present 
whole  numbers  to  the  reader,  without  distracting  his  at- 
tention by  decimal  parts.  For  those,  however,  who  wish 
to  be  acquainted  with  the  exact  English  quantities,  a  table 
is  here  given  below. 

1  lb.  English  is  equal  to  0907 19  lb.  Hessian;  hence, 
about  one-tenth  less  than  the  latter. 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

200 


lb.  Hessan  is  equal  to 
lbs.  Hessian  are  equal  to 


1102  lb. 

English. 

2-204  lbs 

(( 

3-306 

11 

4-409 

u 

5-511 

u 

6-612 

It 

7716 

t< 

8-818 

u 

9-92 

u 

11  02 

a 

22-04 

u 

3306 

u 

44-09 

<c 

5511 

(( 

66-12 

tc 

77-16 

u 

8818 

(C 

99-29 

It 

110-2 

(( 

220-4 

C( 

TABLES. 


417 


300  lbs.  Hessian  are  equal  to  330-6  lbs.  English. 

400  ..  .  440-9  ** 

500  ...  551-1  « 

600  ..  .  661-2  « 

700  ...  771-6  " 

800  ..  .  881-8  " 

900  .  .  .  9920  " 


1000 


11020 


it 


SQUARE   FEET. 

The  Hessian  acre  is  equal  to  40,000  Hessian  square 
feet,  or  26,911  English  square  feet ;  1  English  square  foot 
being  equal  to  1  -4864  Hessian.  The  following  is  a  Table 
to  save  the  trouble  of  calculation.  The  table  is  only  stated 
to  the  figure  10,  but  by  removing  the  decimal  point  one  or 
two  figures,  the  whole  series  given  in  the  case  of  the 
pounds  will  also  be  obtained. 

1  Square  Foot  Hessian  is  equal  to  0-673  Square  Foot  English. 
_   -  ^  jj 

feet 
{( 

a 

It 

u 

a 

tc 

u 


2  feet     . 

.      1-345 

3       . 

. 

.            . 

2-018 

4 

.      2-691 

5       . 

• 

•            . 

3-363 

6 

.      4036 

7       . 

• 

•            • 

4-709 

8 

.      5-382 

9       . 

• 

•            • 

6-054 

10 

.      6-727 

CUBIC 

FEET. 

One  English  cubic  foot  contains  1*81218  of  a  Hessian 
cubic  foot  ;  the  Hessian  and  English  cubic  inch  may  be 
considered  as  equal,  one  English  cubic  inch  containing 
1*048715  Hessian  cubic  inch. 

1  cubic  foot  Hessian  is  equal  to  0-551  cubic  foot  English. 

2  feet  . 

3  ... 

4  .  .  . 

5  ... 

6  •  •• 

7  ... 

8  .  .  . 

10  .  .  . 


1103 

« 

1-655 

i( 

2-207 

feet. 

2-759 

<( 

3-311 

u 

3-863 

cc 

4415 

(( 

4-966 

(( 

5518 

(( 

418 


TABLES. 


TABLE    OF    THE   CORUESPONDING   DEGREES    ON    THE    SCALES   OF 
FAHRENHEIT,  RJ^AUMUR,  AND  CELSIUS,  OR  CENTIGRADE. 


1 

SO) 

52 

•4J 

O 
65 

212 

80 

100 

149 

50 

8 

10 

203 

76 

95 

140 

48 

60 

41 

4 

5 

194 

72 

90 

131 

44 

55 

32 

0 

0 

185 

68 

85 

122 

40 

50 

23 

—  4 

—  5 

176 

64 

80 

113 

36 

45 

14 

—  8 

—  10 

167 

60 

75 

104 

32 

40 

5 

—  12 

—  15 

158 

56 

70 

95 

28 

35 

4 

—  16 

—  20 

86 

24 

30 

—  13* 

—  20 

—  25 

77 

20 

25 

—  22 

—  24 

—  30 

68 

16 

20 

-31 

—  28 

—  35 

59 

12 

15 

—  40 

—  32 

—  40 

—  Denotes  below  the  cipher  on  Fahrenheit's  scale. 


INDEX. 


ACI 


ALK 


.Abnormal f  meaning  of  the  term, 

140. 
Absorption,  by  roots,  107. 

Of  salts,  116. 
Acetone,  306. 
Acid,  acetic,  emitted  by  plants,  150. 

I         compound  atom  of,  301. 

transformation  of,  306. 

formation  of,  329-334. 

Apocrenic,  31. 

Boracic,  122. 

Carbonic,  24  -  70. 

contained  in  the  atmo- 
sphere, 28. 

.  decomposed  by  plants. 


43. 

from  respiration,  44. 

from  springs,  29. 

— — '      why     necessary     to 

plants,  105. 
Crenic,  31. 

Cyanic,  transformation  of,  310. 
Cyan  uric,  70. 
Formic,  71,  86,  290. 
Hippuric,  97. 
Humic,  31. 

properties  of,  34. 

Hydrocyanic,  70,  290. 
Hydromellonic,  70. 
Hypochlorous,  293. 
Kinic,  114. 
Kinovic,  301. 
Lactic,  190. 

production  of,  321. 

Meconic,  115. 

Melanic,  326. 

Mellitic,  363. 

Nitric,  source  of,  88. 

Oxalic,  70. 

Phosphoric,  in  ashes  of  plants, 

155. 
Rocellic,  in  plants,  108. 


Acii,  succinic,  363. 

Sulphuric,  action  of,  on    soils, 
208,  248. 

Tartaric,  in  grapes,  108. 
Acids,  action  oi  upon  sugar,  303. 

Arrest  decay,  361. 

Capacity  for  saturation,  108. 

Organic,  in  plants,  27, 107. 

when  formed,  51. 

Acre^  Hessian,  36. 
Adipocire,  88. 
Affinity,  action  of,  71. 

Chemical,  examples  of,  292. 

Weak,  example  of,  293. 
Agave  Americana,  absorbs  oxygen  j 

51. 
Agriculture,  in  China,  193. 

Object  of,  100,  145,  172. 

how  attained,  146. 

Its  importance,  143. 

A  principle  in,  187. 
Air,  access  of,  favored,  65. 

Ammonia  in,  29,  91. 

Carbonic  acid  in,  41. 

Effect  of  upon  juices,  330. 

on  soils,  167. 

Expired  in  phthisis,  73. 

Improved  by  plants,  47. 

Necessary  to  plants,  130. 
Albumen,  96,  contains  nitrogen,  27. 
Alcohol,  effect  of  heat  on,  306. 

Exhaled,  72. 

Products  of  its  oxidation,  327. 

From  sugar,  313. 
Aldehyde,  327. 
Alkalies,  69,  from  granitic  soils,  1 17. 

Presence  of,  indicated,  215. 

Promote  decay  of  wood,  361. 

Quantity  in  aluminous  minerals, 
148. 
Alkaline  Bases,  in  plants,  on  what 
their  existence  depends,  1 12. 


ANA 


420 


AZO 


Alkaline  Bases,  salts  contained  in 
fertile  soils,  153. 

Salts  in  plants,  sources  of,  151. 
Allantoiuy  70. 
Mloxan,  352. 
Alloxantin,  352. 
Alumina^  in  fertile  soils,  147. 

Its  influence  on  vegetation,  147, 

Mistaken  in  ashes,  148. 
Amber y  origin  of,  363. 
Ammelin,  70. 

Ammonia,  70, 86,  carbonate  of,  from 
urine,  191. 

how  fixed,  191. 

Cause  of  nitrification,  338. 

Changes  colors,  87. 

Condensed  by  charcoal,  104. 

Conversion  of,  into  nitric  acid, 
338. 

Decomposition  of  by  plants,  266. 

Early  existence  of,  123. 

Fixed  by  gypsum,  191. 

From  animals,  174. 

Contained  in  beet-root,  «&c.,  93. 

maple  juice,  94. 

stables,  &c.,  192, 

Furnishes  nitrogen,  104. 

Loss  from  evaporation,  99. 

prevented,  280. 

Produced  by  animal  organism, 
123. 

Product  of  decay,  88. 

disease,  408. 

Properties  of,  88. 

Quantity  absorbed  by  charcoal, 
104. 

by    decayed 

wood,  104. 

In  rain  water,  90. 

How  detected,  91. 

Separated  from  soils  by  rain,  104. 

In  snow  water,  91. 

Solubility  of,  89, 

Sulphate  of,  281. 

Transformation  of,  86. 
Ammoniacal  Liquor,  283. 
Amylin^  its  effect,  74. 
Analysis  of  decayed  wood,  359. 

Of  fire-damp,  372. 

Of  fishes,  177. 

Of  horse-dung,  177. 

Of  peat,  185. 

Of  guano,  201. 

Of  lentils,  159. 

Of  oak-wood,  358, 

Of  night-soil,  179. 

Of  salt  water,  124, 


Analysis,  of  soils,  217,  245. 

Of  wood  coal,  367,  368. 
Animal  food,  preservation  of,  330. 

Life,  connexion  of,  with  plants, 
22. 

Bodies,  products  of  decay,  88. 

complex,  302. 

Animals,  excrements  of,  189. 

Nutriment  of,  22. 
Annual  plants,  how  nourished,  135. 
Anthoxanthum   Odoratum,  acid  in, 

97. 
Anthracite,  373. 
Antidotes  to  Poisons,  381. 
Apatite,    156. 
Apotheme^  31. 
Arable  Land,  146. 
Aromatics,  their  influence  on  fer- 
mentation, 343. 
Argillaceous  Earth,  its  origin,  147. 
Arragonite,  transformation  of,  298. 
Arrow  Root,  140. 
Arseniou^  Acid,  action  of,  381. 
Artificial  Manure,  199,  287. 
Ashes,  as  manure,  182,  198. 

Comparative  value  of,  182, 

Of  fir- wood,  111. 

Of  pine  trees,  110. 

Of  plants,  origin  of  salt  in,  125. 

Importance  of  examination   of, 
112. 

Of  wheat,  158. 

used  as  a  manure,  213. 

Of  bones,  183. 

Of  peat,  185. 

Of  coals,  198. 

Phosphate  of  lime  in,  183. 
Assimilation,  of  carbon,  30. 

Of  carbonic  acid,  and  ammonia, 
131. 

Of  hydrogen,  80  -  84. 

Of  nitrogen,  85  -  105. 

Its  power,  140. 
Atmosphere,  ammonia  in,  29,  92. 

'Composition  of,  27. 

How  maintained,  44. 

Composition  is  invariable,  40. 

Carbonic  acid  in  the,  28-41. 

Motion  of,  46. 

Oxygen  in,  26. 
Atoms,  motions  of,  297. 

Permanence  in  position  of,  297. 
Attraction,  powerful,  overcome,  309. 
Azores,  glairin  found  there,  34, 

Carbonic  acid  at  the,  79. 

Silica  in  hot  springs  of,  170. 
Azote,  25. 


BOT 


421 


CAR 


Jlzotized  matter  in  juices  of  plants, 
137. 
Substances,  combustion  o.f,  334. 
Azulmin,  70. 

Bamboo,  silica  in,  171. 

Bark  of  trees,  products  in,  49. 

Barilla,  118. 

Barley^  analysis  of,  155. 

Barruel,   his   experiments   on   the 

blood,  403. 
Base,  what,  69,  106. 
Bases,  alkaline,  in  plants,  on  what 
their  existence  depends,  112. 

Organic,  27. 

Oxygen  contained  in,  106. 

In  plants,  108. 

Substitution  of,  109. 
Beans,  alkalies  in,  159. 

Nutritive  power  of,  159. 
Becquerel,  experiments  of,  150. 
Beech,  ashes  of,  182. 
5cer,  347-357. 

Bavarian,  348. 

Varieties  of,  347. 
Beet-root  sugar,  38. 

Ammonia  from,  93. 

From  sandy  soils,  140. 
Belgium,  soils  of,  241. 
Benignant  Disease,  402. 
Benzoic  acid,  formed,  97. 
Berzelivs,  humic  extract  of,  34. 

His  analysis  of  bones,  158. 
Birch  Tree,  ammonia  from,  94. 
Bischqff,  estimate  of  carbonic  acid, 

&c  ,  29. 
Blake,  on  nitrate  of  soda,  270. 
Bleaching  Salts,  141. 
Blood,  its  office,  135. 

Action  of  chemical  agents  upon, 
396. 

Its  feeble   resistance  to  exterior 
influences,  396. 

Organic  salts  in,  375. 

Its  character,  386. 
Blossoms,  when  produced,  68. 

Increased,  132. 

Removal  of,  from  potatoes,  134. 
Bones,  dust  of,  183. 

Durability  of,  204. 

Gelatine  in,  203. 

Use  in  composts,  212. 

Composition  of,  157,  158. 
Bouquet  of  wines,  342. 
Boracic  Acid,  122. 
Botanists,  neglect  of  chemistry  by, 

36 


Bran,  use  of,  185. 
Brandy,  from  corn,  342. 

Oil  of,  342. 
Brazil,  wheat  in,  153. 
Bread,  from  wood,  133. 
Brown  Coal,  185. 
Buckicheat,  ashes  of,  159. 
Bulbsj  how  nourished,  76. 

Calcareous  Spar,  208. 

Calcium,  fluoride  of,  157. 

Chloride  of,  192. 
Calculous  Disorders,  74. 
Calico  Printing,  use  of  cow -dung 
in,  186. 

Use  of  phosphate  of  soda  in,  286. 

Substitute  for,  186,  286. 
Caoutchouc,  in  plants,  78. 
Carbon,  24. 

Afforded  to  the  soil  by  plants,  76. 

Assimilation  of,  30  -  63. 

Combination  of,  with  oxygen,  24. 

Of  decaying  substances  seldom 
affected  by  oxygen,  360. 

Derived  from  air,  44. 

In  decaying  wood,  360. 

In  decaying  woody  fibre,  361. 

In  sea- water,  45. 

Oxide  of,  formed,  305. 

Quantity  in  grain,  38. 

in  land,  39. 

in  straw,  38. 

given  off  by  man,  41. 

Restored  to  the  soil,  76. 

Received  by  leaves,  43. 

Its  affinity  for  oxygen,  328. 
Carbonate  of  ammonia  decomposed 
by  gypsum,  100. 

Of  soda,  207. 

Of  lime  in  caverns  and  vaults, 
128. 
Carbonic  acid,   70,   in   the    atmo- 
sphere, 28. 

In  St  Michaels,  79. 

Changes  in  leaves,  142. 

Decomposed  by  plants,  43. 

Emission  of,  at  night,  49. 

Evaporation  of,  56. 

Evolution  from  decaying  bodies, 
328. 

From  decaying  plants,  84. 

excrements,  99. 

humus,  65. 

respiration,  72. 

springs,  29,  85. 

woody  fibre,  64. 

Quantity  extracted  from  air,  45. 


CON 


422 


DAU 


Carbonic  Jlcid^  influence  of  light 
on  its  decomposition,  53. 

Increase  of,  prevented,  4'2. 
Carbon  of  Plants  j  source  of,  260  - 

285. 
Carburetted    hydrogen    with    coal, 

372. 
Caverns,  stalactites  in,  127. 
Charcoal,  what,  24. 

Condenses  ammonia,  104. 

Experiments  of  Lucas  on,  249. 

May  replace  humus,  78. 

Theory  of  its  action,  78. 

Promotes  growth  of  plants,  249. 
Chelmsford,  analysis  of  soil  of,  246. 
Chemical  effects  of  light,  141. 

Forces  can  replace  the  vital  prin- 
ciple, 75. 

Processes  in  nutrition  of  vege- 
tables, 22. 

Transformations,  69,  289. 
Chemistry,  definition  of,  21. 

Organic,  what  is,  22. 

Neglected  by  botanists,  55  j  and 
physiologists,  56. 
China,  its  agriculture,  193. 

Collection   and   use  of  manure 
in,  193. 
Chlorine  gas,  141  ;  effect  of,  101. 
Chloride  of  calcium,  192. 

Of  nitrogen,  293. 

Of  potassium,  its  effect,  116. 

Of  sodium,  its  volatility,  123. 
Clay,  burned,  advantages  of,  as  a 

manure,  102. 
Clays,  potash  in,  148. 
Clay  slate,  157. 
Coal,  formation  of,  369. 

Ammoniacal  liquor  from,  205. 

Inflammable  gases  from,  372. 

Origin  of  substances  in,  363. 

Of  humus,  30,  129. 

Wood  or  brown,  185. 
Colors  of  flowers,  96. 
Combustion  at  low  temperatures, 
327. 

Of  decayed  wood,  362. 

Induction  of,  332. 

Removes  oxygen,  42. 

Spontaneous,  324. 
Compost  manure,  118,  212,  279. 
Concretions  from  horses,  156. 
Constituents  of  plants,  24. 
Consumption,  73. 

Contagion,    reproduction     of,     on 
what  dependent,  389. 


Contagion,  susceptibility   to,  how 

occasioned,  401. 
Contagions,  how  produced,  389. 

Propagation  of,  398. 
Contagious  matters,  action  of,  394, 
399,  413. 

Their  effects  explained,  390. 

Life  in,  disproved,  392. 

Reproduction  of,  392. 
Copper  alloy,  its  action,  on  sulphu- 
ric acid,  292. 
Corn,  how  cultivated  in  Italy,  152 

Phosphate  of  magnesia  in,  156. 

Effect  of  carbonic  acid  on,  79. 
Corn  brandy,  342. 
Corrosive  sublimate,  action  of,  381. 
Cow,  excrements  of  the,  120,  176, 
178. 

Variable  in  value,  179. 

Urine  of  the,  177;  rich  in  potash, 
119. 
Cow-pox,  action  of  virus  of,  405. 
Crops,  rotation  of,  161 . 

Favorable  effects  of,  162. 

Principles  regulating,  174,  275. 
Cubic  nitre,  270. 
Cultivation,  its  benefits,  47. 

Different  methods  of,  144. 

Object  of,  145. 
Culture,  art  of,  126. 

Of  plants,  principles  of  the,  144. 
Cyanic  acid,  transformation  of,  311. 
Cyanogen,  combustion  of,  335. 

A  compound  base,  70. 

Transformation  of,  311. 
Cyanuric  acid,  70. 

Dana,  Dr.  S.  L.,  on  geine,  31. 

On  phosphate  of  lime,  182. 

On  ammonia,  259. 

On  phosphate  of  soda  in  calico 
printing,  286. 
Daniel's  manure,  287. 
Darwin,  on  nitrate  of  soda,  270. 
Daubeny,  experiments  of,  105. 

On  forest  trees,  164. 

On  nutritive  qualities  of  plants, 
265. 

On  source  of  carbon,  285. 

On    source  of  carbon  of  plants, 
260. 

On  source  of  hydrogen  of  plants^ 
263. 

Carbon  of,  260. 

Experiments  at  Oxford,  257. 

Experiments  on  his  farm,  273. 

Source  of  hydrogen,  263. 


EXC 


423 


FRU 


Davisj    his    account    of    Chinese 

manure,  193. 
Death  from  nutritious  substances, 
59. 

The  source  of  life,  105. 
DecandoUe,   his   theory   of   excre- 
tion, 163. 

Difference    of    his    views    and 
those  of  Macaire-Princep,  167. 
Decay,  292. 

A  source  of  ammonia,  88. 

Of  wood,  361. 

Of  plants  restores  oxygen,  84. 
and  putrefaction,  291. 
Decomposition.  68,  289. 

Organic,  chemical,  291. 
Dextrine,  56,  57. 
Diamond  J  its  origin,  363. 
Diastase,  136. 

Contains  nitrogen,  136. 
Disease,  how  excited,  386. 
Dog  J  excrement  of  the,  175. 
Dung  hills,  liquid  from,  191. 

Reservoirs,  191. 

Substitute,  187. 

Ebony  wood,  oxygen  and  hy- 
drogen in,  53. 
Effete  matters  separated,  68. 
Eifet,  springs  evolve  carbonic  acid, 

29. 
Elements  of  plants,  24 

Not  generated  by  organs,  59. 
Elphinstoney  Sir  Howard,  on  soda- 
ash  as  a  manure,  207. 
England,  analysis  of  soils  in,  242. 
Equilibrium    of    attractions     dis- 
turbed, 298. 
EquisetacecB  contain  silica,  171. 
Eremacausis,  63,  299. 
Analogous  to  putrefaction,  328. 
Arrested,  323. 
Definition  of,  299. 
Necessary  to  nitrification,  335. 
Of  bodies  containing  nitrogen, 

334. 
Of  bodies  destitute  of  nitrogen, 
329. 
Ether,  oenanthic,  344. 
Etiolation,  46. 
Eudiometer,  90. 
Excrementitious  matter,  production 

of,  illustrated,  71. 
Excrement,    animal,  its    chemical 
nature,  175. 
Of  the  dog,  cow,  &c.,  175. 
Influence  of,  as  manure,  180. 


Excrements  of  plants,  163. 

Conversion  of,  into  humus,  35. 

Of  man,  amount  of,  195. 

Value  of,  189. 

Preservation  of,  193. 
Excretion,  organs  of,  72. 

Of  plants,  theory  of,  163. 
Experiments  in  physiology,  object 
of,  56. 

Of  physiologists  not  satisfactory. 

Extract  of  humus,  31. 

Fallow,  changes  from,  152. 

Crops,  159. 

Time,  159. 
Fattening  of  animals,  146. 
FcBces,  analysis  of,  179. 
Ferment,  313,  314. 
Fermentation,  299,  300. 

Causes  of,  292. 

Of  Bavarian  beer,  348. 

Of  beer,  349. 

Gay-Lussac's    experiments    in, 
330. 

Of  sugar,  313. 

Of  vegetable  juices,  314. 

Vinous,  338. 

Of  wort,  3.39. 
Fertility  of  fields,  how  preserved, 

181. 
Fires,  plants  on  localities  of,  154. 
Firs,  succeed  oaks,  164. 
Firioood,  analysis  of  its  ashes,  111. 
Fishes,  in  salt-pans,  121. 

As  manure,  259 
Flanders,  manure  in,  193. 
Fleabane,  160. 
Flesh,  composition  of,  177. 

Effect  of  salt  on,  377. 
Flour,  bran  of,  185. 
Flowers,  colors  due  to  ammonia,  96. 
Fluorine,  157;    in   ancient  bones,. 

158. 
Foliage,  increased,  101. 
Food,  effect  on  products  of  plants, 
139. 

Of  young  plants,  J  31. 

Transformation  and  assimilation 
of,  72. 
Formation  of  wood,  138. 
Formic  add,  70,  290. 

Theory  of  its  formation,  71 . 

From  hydrocyanic  acid,  71. 
Fossil  resin,  origin  of,  363. 
Franconia,  caverns  in,  127. 
Fruit,  increased,  132. 


HES 


424 


INO 


Fruity  ripening  cf^  83. 

changes    attending, 

132. 
Fulminating  silver,  293. 

Gaseous  substances  in  the  lungs, 

effect  of,  407. 
Gasterosteua  aculeatuSy  in  salt-pans, 

121. 
Gasworks,  liquor  of,  205,  283. 
Gay-Lussac,  his  experiments,  330. 
Geine,  31. 

Germany,  cultivation  in,  ]8l. 
Germination  of  potatoes,  133. 

Of  grain,  137. 
Glair  in,  34. 
Glass,  as  a  manure,  187. 

Effectof  heat  on,297. 
Glue,  manure  from,  184. 
Gluten,  conversion  of,  into  yeast, 
348-356. 

Decomposition  of,  321. 

Gas  from,  339. 
Grain,  germination  of,  137. 

Manure  for,  119. 

Rust  in,  220. 
Chranitic,  soil  affords  alkalies,  117. 
Grapes,  fermentation  of,  338. 

Juice  of,  differences  in,  346. 

Potash  in,  112. 
Grasses,  seeds  of,  follow  man,  121. 

Silica  in,  170. 

Valued  in  Germany,  169. 

Compost  for,.  118. 
Grauwacke,  soil  from,  147. 
Growth  of  plants,   conditions    for 

the,  144. 
Gwano,  95, 199. 

Gypsum,   decomposition    of,    100, 
280. 

Its  influence,  101. 

Use  of,  191. 

Theory  of,  280. 

Substitutes  for,  282, 

Action  of,  247,  280. 

Replaced,  248. 

Hailstones,  91. 

Hay,  carbon  in,  38. 

Contains  nitrogen,  176. 

silica,  155. 

Analysis  of,  38. 
Haystack,  effect  of  lightning  upon 

a,  155. 
Hesse,  custom  in,  213. 
Hessian  and  English  weights  and 
measures,  416. 


Hessian  acre,  36. 
Hibernating  animals,  134. 
Hippuric  acid,  97. 
Horse,  urine  of  the,  102 

Concretions  in  the,  157. 
Horse- dung,  actiop  of  water  upon, 
177. 

Analysis  of,  178. 
Human  fmces,  analysis  of,  179. 
Humate  of  lime,  quantity  received 

by  plants,  37. 
Humic  acid,  31 ,  65,  90. 

Action  of,  129. 

Properties  of,  34. 

Is  not  contained  in  soils,  90. 

Quantity  received  by  plants,  37. 

Insolubility  of,  128. 
Humus,  30,  90. 

Action  of,  63. 

Analysis  of,  32. 

Erroneous'  opinions  concerning, 
49. 

Extract  of,  31. 

Action  upon  oxygen,  127. 

Coal  of,  129. 

Conversion  of  woody  fibre  into, 
358 

How  produced,  358. 

Its  insolubility,  127. 

Properties  of,  34. 

Replaced  by  charcoal,  78. 

Source  of  carbonic  acid,  65. 

Theory  of  its  action,  65. 

Unnecessary  for  plants,  33,  77. 
Hungary,  soils  of,  240. 
Hydrates,  31. 

Hydrocyanic  acid,  70,  290. 
Hydrogen,  assimilation  of,  80-82. 

Properties  of,  25. 

Excess   of  in    wood   accounted 
for,  81. 

Of  decayed  wood,  359. 

In  plants,  263. 

Of  plants,  source  of,  82,  263. 

Peroxide  of,  294. 
Hyett,  Mr.,  on  nitrate  of  soda,  206, 
271. 

Ice,  bubbles  of  gas  in,  54.. 
Indian  corn,  analysis  of,  98. 
Indifferent  substances,  27. 
Inflammable  air,  25. 
Ingenhouss,  his  experiments,  49. 
Inorganic  compounds,  301. 

Action  of,  374. 

In  what  they  differ  from  organic, 
302. 


MAN 


425 


NIT 


Inorganic    constituents    of   plants, 

105,  126. 
Compounds,  stability  of,  301. 
Iodine,  126. 
Iron^  oxide  of,  attracts  ammonia, 

103. 
Irrigation  of  meadows,  effect  of, 

127,  169. 
Itch  insect,  122. 

Jackson^  analysis  of  horse-dung, 
177. 
On  peat  compost,  258. 
Java^  soil  of,  244 . 
Juices  of  vegetables,  27, 

Lactic  acid,  production  of,  321. 

Lava,  soil  from,  149. 

Lead,    salts   of,    compounds    with 

organic  matter,  383. 
Leaves,  absorb  carbonic  acid,  43. 
Ashes  of,  contain  alkalies,  154. 
Cessation  of  their  functions,  68. 
Change  color  from  absorption  of 

oxygen,  68. 
Consequence  of  the  production 

of  their  green  principle,  173. 
Decompose  carbonic  acid,  142. 
Their  office,  135. 
Power  of  absorbing  nutriment, 

how  increased,  67. 
Quantity  of  carbon  received  by, 

45. 
Contain  azotized  matter,  188. 
Lentils,  analysis  of,  159. 
Life,  notion  of,  392. 
Light,  absence  of,  its  effect,  49. 
Chemical  effects  of,  105,  142. 
Influences  decomposition  of  car- 
bonic acid,  53. 
Lime,  phosphate  of,  183,  184,  212. 
Limestone,  analysis  of,  153. 
Lixiviation,  182. 

Lucern,  phosphate  of  lime  in,  159. 
Benefits    attending  its   culture, 
172. 
Lucas,  his  experiments,  249. 

MaCAIRE-PRINCEP,  his  experi- 
ments, 164,  256. 
Magnesia,  phosphate  of,  in  seeds, 

62. 
Maine,  analysis  of  soil  of,  246. 
Mannite,  139. 
Manure,  174,  208. 

Animal,  yields  ammonia,  95, 278. 
Artificial,  204,  212,  237. 

36* 


Manure,  components  of,  should  be 
known,  144. 

Carbonic  acid  from,  99. 

Human,  284. 

Of  the  Chinese,  193. 

Effect  of,  173. 

Bone,  183. 

Daniell's  artificial,  287. 
Manuring  of  vines,  253,  254. 
Maple  juice,  ammonia  from,  94. 

Trees,  sugar  of,  94. 
Meadoios,  irrigation  of,  127,  169. 
Medicine,  action   of,  remedies  in, 

186. 
Meconic  acid,  115. 
Melam,  70. 
Melamin,  70. 
Melitic  acid,  363. 
Mellon,  70. 
Merrimack  Manuf.  Co.,  first  use  of 

phosphate  of  soda  by,  286. 
Metallic    compounds    required     by 

plants,  60. 
Metamorphosis,  291. 
Miasm,  defined,  407. 
Michaels,  St.,  carbonic  acid  at,  79. 
Minerals  attract  ammonia,  103. 
Morbid  poisons,  389. 
Motion,  its  influence  on  chemical 

forces,  296. 
Mould,  vegetable,  363. 

Conversion  of  woody  fibre  into, 
364. 

Condenses  ammonia,  104. 
Mouldering  of  bodies,  365. 
Must,  fermentation  of,  340. 

Naples,  soils  of,  152,  285. 
Mght-soil,  193,  199,  259,  284. 
NUe,  soil  of  its  vicinity,  168. 
Nitrate  of  soda  as  a  manure,  206. 

Theory  of  its  formation,  277. 

Of  Peru,  270,  277. 

Experiments  with,  271. 
Nitrated  wheat,  272. 

Flour,  275. 
Nitric  acid  from  ammonia,  336. 

Animals,  88. 

How  formed,  335. 
Nitrification,  334, 

Condition  for,  336. 
Nitrogen  from  animals,  87. 

Absorption  of  by  plants,  267. 

Account  of,  25 

Application  of  substances  con- 
taining it,  99. 

Assimilation  of,  85,  97. 


OXY 


426 


PLA 


J^itrogen^  chloride  of,  293. 

Characteristic  of,  25. 

Compounds  of,  25,  27. 

,    peculiarity    in, 

319. 

In  albumen,  27. 

From  the  atmosphere,  88. 

In  plants,  25,  27,  265. 

Source  of,  283,  285. 

Production  of,  the  object  of  agri- 
culture, 99. 

Transformation  of  bodies  con- 
taining, 305. 

of    bodies    not 

containing,  305. 

In  rice,  98. 

In  solid  excrements,  189. 
In  urine,  189. 
JVutrition,  conditions  essential  to, 
22,  59. 
Inorganic     substances    required 

in,  60. 
Superfluous,  how  employed,  67. 
Of  young  plants,  172. 

Oaks,  ashes  of,  154. 

Excretions  of,  49. 

Dwarf,  66. 

Followed  by  firs,  164. 
Oak-wood  affords  humic  acid,  35, 

Composition  of,  358. 

Mouldered,  analysis  of,  359. 
Odor  of  substances,  345. 

Of  gaseous  contagious  matter, 
408. 
(Enanthic  ether,  344. 
Ohio,  analysis  of  soils  of,  245. 
Orcin,  325. 

Organs  of  excretion,  72. 
Organic  acids,  26. 

Decomposition  of,  295. 

Chemistry,  21,22. 
Compounds,  82. 

Compared   with  inorganic  salts 
in  plants,  301. 
Organized  bodies  do  not  generate 

substances,  68. 
Osmazome^  317. 
Oxalic  acid,  70. 
Oxford,  experiments  at,  257. 
Oxamide,  decomposition  of,  391. 
Oxides,  metallic,  in  fir- wood,  111 . 
Oxygen,  26. 

Action  on  alcohol,  327. 

Properties  of,  26. 

Absorption  of,  at  night,  51 


Oxygen  J  absorption  by  respiration, 
72. 

leaves,  51. 

plants,  49. 

wood,  358. 

Action  upon  woody  fibre,  359. 

Its  action  in  decomposition,  331. 

Emitted  by  leaves,  43. 

Given  to  air  by  land,  80. 

Extracted  from  air  by  mould,  364. 

In  air,  28. 

Consumption  of,  40,  41. 

In  water,  82. 

Promotes  decay,  130. 

Separated  during  the  formation 
of  acids,  83. 

Is  furnished  by  the  decomposi- 
tion of  water,  81. 

PaYEN,  his  table  of  composition 

of  woods,  264. 
Peat,  compost  of,  118,  258. 

Analysis  of,  185. 
Perennial  plants,  how  nourished, 

135. 
Peroxide,  what,  295. 
Peroxide  of  hydrogen,  294. 
Peterson  and  Schodler^' their  analy- 
sis of  woods,  52. 
Phosphates  necessa.ry  to  plants,  155. 
Phosphate    of  iron,   the    probable 
cause  of  rust,  221. 
In  pollen,  182. 
Phosphate  of  lime  in  teak  wood, 
156. 
In  forest  soils,  182. 
Phosphoric  acid  in  ashes  of  plants, 

155. 
Phthisis,  remedies  in,  73. 
Physiologists,  their  experiments  not 
satisfactory,  62. 
Neglect  of  chemistry  by,  56. 
Pipe-clay,  ammonia  in,  103. 
Plants  absorb  oxygen,  50. 
Ashes  of,  salts  in,  110. 
Conditions   necessary   for  their 

life,  62. 
Constituents  of,  24. 
Decay  of,  a  source  of  oxygen,  84. 
Decompose  carbonic  acid,  43. 
Development  of,  requisites  for, 

27,  117,  136,  143. 
Effect  of,  on  rocks,  150. 
Elements  of,  24. 
Emit  acetic  acid,  150. 
Exhalation     of     carbonic     acid 
from,  53. 


PRO 


427 


SAT 


Plants,  of  a  former  world,  76. 

Formation  of  their  components, 
83. 

Functions  of,  44. 

Improve  the  air,  47. 

Influence  of  gases  on,  50. 

■  of  shade,  50. 

Inorganic  constituents  of,  105. 

Life  of,  connected  with  that  of 
animals,  22. 

Milky-juiced,  in  barren  soils,  78. 

Nutritive   qualities   of,    depend- 
ence on  nitrogen,  265. 

Organic  acids  in,  26,  106. 

salts  in,  108. 

Perennial,  nourished,  135. 

Products  of,  vary,  139. 

Size  of,  proportioned  to  organs 
of  nourishment,  66. 

Sources   of  their   nourishment, 
27. 

Succession  of,  its  advantage,  162. 

Vital  processes  of,  84. 

Wild,  obtain  nitrogen  from  the 
air,  99. 

Yield  oxygen,  48. 
Platinum  does  not  decompose  nitric 

acid,  292. 
Ploughing,  its  use,  130. 

Recommended  by  Cato,  270. 
Poisons  generated  by  disease,  374. 

Inorganic,  374  -  379. 

Peculiar  class  of,  384. 

Rendered  inert  by  heat,  389. 
Poisoning,  superficial,  379. 

By  sausages,  387. 
Pompeii,  air  from,  41. 

Bones  from,  158. 
Potash,  action  of,  upon  mould,  364. 

In  limestones,  153. 

In  grapes,  112. 

•Ley  of,    its    effects    on    excre- 
ments, 99. 

Presence  of,  in  plants,  accounted 
for,  148. 

Replaced  by  soda,  113. 

Required  by  plants,  62. 

Quantity  in  soils,  148. 

Silicate  of,  in  soils,  62. 

Sources  of,  148. 
Potatoes,  oil  of,  341. 

Effect  of,  as  food,  139. 

Analysis  of,  114. 

Germination  of,  133. 

Produce  of,  increased,  134. 
Poudrette,  199. 
Products  of  transformations,  69. 


Prince,  J.  D.,  first  to  apply  phos- 

phate  of  soda,  &c.,  280. 
Purgative  eflfect  of  salts  explained, 

377. 
Pus,  globules  in,  397. 
Pv^ey,  Mr.,  on  nitrate  of  soda,  206. 
Putr^action,  63,  299,  300. 
Of  animals,  174. 
Causes  of,  292. 
Communicated,  389. 
Source  of  ammonia,  104. 

carbonic  acid,  99. 

Putrefying  sausages,   death  from, 

387;  their  mode  of  action,  388. 

Substances,     their     effect      on 

wounds,  389 
alkaline,  397. 


-  acid,  397. 


Radical,  what,  69. 

Rain-water,  alkali  extracted  by,  150. 

Reduction  of  oxides,  294. 

Reeds  and  canes  require  silica,  155. 

Removal  of  branches,  effects  of,  132. 

Reservoirs  of  dung,  191. 

Respiration,  oxygen  consumed  by, 

41. 
Rhine,  soils  in  its  vicinity,  168. 

Wines,  342. 
Rice,  analysis  of,  98. 
Ripening  of  fruit,  132. 
Root  secretions,  163;  256 
Roots  absorb,  107. 

Emit    excrementitious    matter, 
163. 

Their  ofliice,  125. 

Secretions  of,  256. 
Rotation  of  crops,  161,  174. 

Sal  ammoniac,  as  manure,  282. 

Saliculite  of  potash ,  326. 

Saline  plants,  121. 

Salsola  kali,  113. 

Salt,  volatilization  of,  123. 

Salts,  absorption  of,  116. 

Effect  of,  on  the  organism,  375. 

on  flesh,  377. 

on  the  stomach,  377. 

Organic,  in  plants,  27. 

in  the  blood,  376. 

Passage  of  through  the   lungs, 
376. 
Salt-works,  loss  in,  124. 
SaltiDort,  122. 
Sand,  plants  in,  78. 
Sandy  soil,  decay  of  wood  in,  361. 
Saturation,  capacity  of,  106. 


STA 


428 


TOB 


Sausages,  poisonous,  387. 
Saussure^  his  experiments  on  air,  42. 

Analysis  of  pines,  110. 

On  the  growth  of  plants,  158. 
Schubler,  his  observations  on  rain, 

90. 
Sea-water,  analysis  of,  124. 

Contains  carbon,  45. 

Contains  ammonia,  125. 
Secretions,  root,  256. 
Silica,  170,  in  grasses,  155. 

Solution  of,  170. 

In  reeds  and  canes,  155. 
Silicate  of  potash  in  plants,  62. 

As  a  manure,  187,  212,  213. 
Siliceous  sinter ^  170. 
Silver,  carbonate  of,  action  on  or- 
ganic acids,  295. 

Salts,  poisonous  effects  of,  382. 
Simple  bodies,  21. 
Sinapis  alba,  410. 
Size  of  plants  proportional  to  organs 

of  nourishment,  66. 
Smell,  what,  345. 
Snow-water,  ammonia  in,  91. 
Soda  may  replace  potash,  113. 

Nitrate  of,  theory  of  its  forma- 
tion, 277. 

Phosphate  of,  in  calico  printing, 
286. 
Soda-ash,  207. 

Soils,  advantage  of  loosening,  65, 
130. 

Chemical  constituents  of,  208. 

Best  for  meadow- land,  118. 

Carbon  restored  to,  75. 

Chemical  nature  of  its  influence, 
167. 

Constituents  of,  208. 

Exhaustion  of,  151. 

Ferruginous,  improved,  130. 

Fertile,  contain  phosphoric  acid, 
potash,  &c.,  242,  243. 

Fertile,  of  Vesuvius,  149. 

From  lava,  149. 

Of  heaths,  223. 

Imbibe  ammonia,  99. 

Improved  by  crops,  161. 

Impoverished  by  crops,  161. 

Various  kinds  of,  208. 
Stagnant  water,  effect  of,  130. 
Stalactites  in  caverns,  127. 
Starch,  56 ;  composition  of,  83. 

Accumulation  of,  in  plants,  132. 

Development    of    plants    influ- 
enced by,  134. 

Effect  of,  on  malt,  74. 


Starch,  vesicles  in,  56. 

Product  of  the  life  of  plants,  49. 

In  willows,  133. 
Staunton,  Sir  G.,  on  Chinese  ma- 
nure, 194. 
Straw,  analysis  of,  38. 
Struve,  experiments  of,  151. 
Substitution  of  bases,  109. 
Subsoil  ploughing,  215,  269. 
Succession  of  crops,  275. 
Succinic  acieZ,  363. 
Sugar,  action  of  alkalies  upon,  303. 

acids  upon,  303. 

Composition  of,  313. 

Carbon  in  sugar,  38. 

Contained  in  the  maple-tree,  93. 

In   clerodendron  fragrans,  &c., 
138. 

Devolopment  of  plants,  influence 
on,  134. 

Fermentation  of,  313. 

Formic  acid  from,  86. 

In  beet- roots,  93. 

Metamorphosis  of,  313. 

Organic    compounds,    all    form 
sugar,  302. 

Product  of  the  life  of  plants,  49. 

Transformation  of,  304. 

When  produced,  67. 
Sulphur,  crystallized,  dimorphous, 
297. 

In  plants,  214. 
Sulphuric  Acid,  action  of,  on  soils, 

208,  248. 
Sulphurous  Acid  arrests  decay,  360. 
Swamp  muck,  185. 
Sweden,  soils  of,  243. 
Swine,  urine  of,  202. 
Synaptas,  411. 

TABASHEER,  171. 

Tables,  of  Hessian    and  English 

weights,  41 6. 
Tannic  Acid,  83. 
Tartaric  Acid,  83. 
Converted  into  sugar,  83. 
In  wine,  342. 
Teak  Tree,  salts  found  in,  155. 
Teeth,  analysis  of,  158. 
Teltowa  Parsnep,  66,  140. 
Thenard,  his  experiments  on  yeast, 

313. 
Thermometers,  scales  of,  418. 
Tin,  action  on  nitric  acid,  292. 
Tobacco,  juice  contains  ammonia, 

94. 
Leaves  of,  345. 


VIN 


429 


woo 


Tobacco^  value  of,  proportional  to 
quantity  of  potash  in  tiie  soil, 

Nitric  acid  in,  97. 

In  Virginia,  151. 
Transformation,  by  heat,  306. 

Chemical,  71,  iiiil. 

Chemical  transformations  differ 
from  decompositions,  71. 

Of  acetic  acid,  306. 

Of  arragonite,  298. 

Of  carbonic  acid,  142. 

Of  meconic  acid,  306. 

Not  affected  by  the  vital  princi- 
ple, 74. 

Explained,  74. 

Of  bodies  containing  nitrogen, 
305. 

Of  bodies  destitute  of  nitrogen, 
305. 

Results  of,  75. 

Of  sugar,  303. 

Of  wood,  306. 

Of  cyanic  acid,  311. 

Of  cyanogen,  311. 

Of  gluten,  339. 
Transplantation^  effect  of,  132. 
Trees,  diseases  of,  137. 

Require  alkalies,  154. 

ULMIN,  30. 

Urea^  70,  87 ;    converted  into  car- 
bonate of  ammonia,  97. 

In  urine,  189. 
Uric  Acid,  yields  ammonia,  192. 

Transformations  of,  193. 
Urinary  calculi,  treatment  of,  74. 

Organs,  eliminate  nitrogen,  73. 
Urine  J  contains  nitrogen,  97. 

Its  use  as  a  manure,  95, 201, 211. 

Of  men,  &c.,  190. 

Of  horses,  202. 

Human,  analysis  of,  190. 

Of  cows,  202. 

Its  use  in  China  and  Flanders, 
95,  194. 

Of  swine,  202. 

Vaccination,  its  effect,  405. 

Vegetable  Albumen,  9Q. 

Life,  one  end  of,  23. 

Mould,  363. 

Juices,  fermentation  of,  314. 
Vesuvius,  fertile  soil  of,  149. 
Vines,  new  mode  of  manuring,  253. 

Juice  of,  yields  ammonia,  94. 
Vinous  Fermentation^  338. 


Virginia,  early  products  of  its  soils, 

151. 
Virus,  of  small  pox,  405. 

Vaccine,  405. 
Vitality,  what,  59. 
Vital  Principle,  73. 

Value  of  the  term,  75. 

How  balanced  in  the  blood,  374. 
Vital  Processes  of  plants,  166. 
Voelckel,  his  analysis  of  guano,  96. 

Water,    carbonic    acid    of,    ab- 
sorbed, 44. 
Composition  of,  81. 
Dissolves  mould,  364. 
Freezing  of,  296. 
Plants,  their  action  upon,  56. 
Rain,  contains  ammonia,  91. 

required  by  plants,  28. 

required  by  gypsum,  102. 

Hard,  made  soft,  92. 

Salt,  analysis  of,  124. 
Wavellite,  156. 
West  Indies,  soil  of,  244. 
Wheat,  analysis  of,  154. 

Ashes  of,  used  as  a  manure,  213. 

Exhausts,  152. 

Nitrated,  272. 

Gluten  of,  94. 

Manure  for,  213. 

Why  it  does  not  thrive  on  cer- 
tain soils,  153. 

In  Virginia,  151. 
Wilbrand,  Dr.^  on  maple  sugar,  93. 
Willows,  growth  of,  133. 
Wine,  effect  of  gluten  upon,  347. 

Fermentation  of,  347. 

Properties  of,  347. 

Substances  in,  341. 

Taste  and  smell,  342. 

Varieties  of,  1342. 
Wood,  decomposition  of,  320. 
Wohler,  his  analysis  of  limestone, 

153. 
Wood  charcoal,  may  replace   hu- 
mus, 78. 

a  manure,  249. 

Decayed  combustion  of,  362. 

Absorbs  ammonia,  104. 

Analysis  of,  52. 

Bread  from,  133. 

Composition  of,  264. 

Conversion  of,  into  humus,  335. 

Decay  of,  357. 

Requires  air,  358. 

Decomposition  of,  320. 

Elements  of,  358,  360. 


WOR 


430 


ZIN 


Woody  transformation  of,  306. 

Effect  of  moisture  and  air  on, 
358.  ^ 

Formation  of,  138. 

Source  of  its  carbon,  39. 
Wood  Coaly  how  produced,  365. 

Analysis  of,  367,  368. 
Woody  Fibre,  changes  in,  358. 

Composition  of,  358. 

Decomposition  of,  358. 

Formation  of,  48. 

Moist,  evolves  carbonic  acid,  358. 

Mould  from,  364. 
Wormwood y  effect  of  its  culture, 
120. 


Worty  fermentation  of,  350. 
Wounds,  effect  of  putrefying  sub- 
stances on,  386. 

YEASTy  315. 
Destroyed,  341. 
Experiments  on,  316. 
Formed,  340. 
Its  mode  of  action,  318. 
Its  production,  315. 
Two  kinds  of,  350. 

Zeine,  98. 

ZinCy  decomposition  of  water  with, 

84. 


PROFESSOR  LIEBIG'S 
REPORT  ON  ORGANIC  CHEMISTRY. 


NOTICES   OF  PART  I. 
AGRICULTURAL  CHEMISTRY. 

This  work  has  already  acquired  great  reputation  in  Great 
Britain,  and  several  notices  and  reviews  of  it  have  appeared 
in  the  foreign  journals,  all  of  which  unite  in  expressing  their 
high  estimation  of  its  contents.  Three  lectures  have  been 
recently  delivered  on  Agriculture  at  Oxford  by  Dr.  Daubeny, 
the  distinguished  Professor  of  Chemistry  and  Botany,  in  which 
he  has  illustrated  and  adopted  Professor  Liebig's  views. 


'*  Every  page  contains  a  mass  of  information.  I  would 
earnestly  advise  all  practical  men,  and  all  interested  in  culti- 
vation, to  have  recourse  to  the  book  itself  The  subject  is 
vastly  important,  and  we  cannot  estimate  how  much  may  be 
added  to  the  produce  of  our  fields  by  proceeding  on  correct 
principles."  —  Loudon's  Gardener^ s  Magazine  for  March, 
1841. 


In  alluding  to  this  work,  before  the  British  Association  for 
the  Advancement  of  Science,  Dr.  Gregory  remarked  ;  — 

**  Every  thing  was  simply  and  clearly  explained.  It  was 
the  first  attempt  to  apply  the  newly  created  science  of 
Organic  Chemistry  to  Agriculture.  In  his  opinion,  from 
this  day  might  be  dated  a  new  era  in  the  art,  from  the  prin- 
ciples established  by  Professor  Liebig.  He  was  of  opinion, 
that  the  British  Association  had  just  reason  to  be  proud  of 
such  a  work,  as  originating  in  their  recommendation." 


The  followins:  is  from  the  address  at  the  Anniversary 
Meeting  of  the  Royal  Society,  November  30,  1840,  when 
one  of  the  Copley  medals  was  awarded  to  Professor  Liebig, 
in  presenting  which,  the  President,  the  Marquis  of  Northamp- 
ton, thus  addressed  Professor  Daniell,  who,  in  the  absence 
of  Professor  Liebig,  received  for  him  the  medal;  — 


2 

*'  I  hold  in  my  hand  and  deliver  to  you  one  of  the  Copley 
medals,  which  has  been  awarded  by  us  to  Professor  Liebig. 
My  principal  difficulty,  in  the  present  exercise  of  this,  the 
most  agreeable  part  of  my  official  duty,  is  to  know,  whether 
to  consider  M.  Liebig's  inquiries  as  most  important  in  a 
chemical  or  in  a  physiological  light  ;  however  that  may  be, 
he  has  a  double  claim  on  the  scientific  world,  enhanced  by 
the  practical  and  useful  ends  to  which  he  has  turned  his 
discoveries." 


*' It  is  the  best  book,"  writes  Mr.  Nuttall,  **ever  pub- 
lished on  Vegetable  Chemistry  as  applied' to  Agriculture, 
and  calculated  undoubtedly  to  produce   a  new  era  in  the 


science." 


Extract  from  a  letter  from  Mr.  Colman,  Commissioner  for 
the  Agricultural  Survey  of  Massachusetts,  dated  February 
15th,  1841; — 

*'It  is  the  most  valuable  contribution  to  Agricultural  sci- 
ence, which  has  come  within  my  knowledge.  It  takes  new 
views  on  many  subjects,  which  have  been  long  discussed 
without  any  progress  towards  determinate  conclusions ;  and 
reveals  principles,  which  are  of  the  highest  importance. 
Some  of  these  principles  require  further  elucidation  and 
proof;  but,  in  general,  they  are  so  well  established  by  facts 
within  my  own  observation,  that  in  my  opinion  the  truth,  if 
not  already  reached,  is  not  far  distant." 


From  Silliman's  Journal,  January,  1841 ;  — 

''It  is  not  too  much  to  say,  that  the  publication  of  Profes- 
sor Liebig's  Organic  Chemistry  of  Agriculture,  constitutes 
an  era  of  great  importance  in  the  history  of  Agricultural 
science.  Its  acceptance  as  a  standard  is  unavoidable,  for ,  fol- 
lowing closely  in  the  straight  path  of  inductive  philosophy,  the 
conclusions  which  are  drawn  from  its  data  are  incontrovertible," 
—  ''To  some,  the  style  of  this  work  may  seem  somewhat 
obscure  ;  but  it  will  be  found,  on  a  re-perusal,  that  great 
condensation,  brevity,  and  terseness,  have  been  mistaken 
for  obscurity." — "We  can  truly  say,  that  we  have  never 
risen  from  the  perusal  of  a  book  with  a  more  thorough  con- 
viction of  the  profound  knowledge,  extensive  reading,  and 
practical  research  of  its  author,  and  of  the  invincible  power 
and  importance  of  its  reasonings  and  conclusions,  than  we 
have  gained  from  the  present  volume." 


In  the  notice  from  which  the  foregoing  is  extracted,  the 
learned  editors  enumerate  among  the  most  important  chap- 
ters, those  on  manure,  the  composition  of  animal  manure, 
the  essential  elements  of  manure,  bone  manure,  the  supply 
of  nitrogen  by  animal  matter,  mode  of  applying  urine,  value 
of  human  excrements,  &;c. 

The  Second  Part  of  the  work  is  a  masterpiece  of  con- 
densed reasoning  on  chemical  transformations,  fermentation, 
decay,  and  putrefaction,  and  on  contagion,  poisons,  and 
miasms. 

From  the  Farmer's  Register,  Petersburg,  Va.,  August, 
1841  ;  — 

**  This  work  of  Professor  Liebig  has  received  more  re- 
spectful attention  and  applause,  than  any  on  Agriculture  that 
has  issued  from  the  press." —  **No  work  have  we  yet  seen 
that  furnished  to  Agriculturists  a  more  abundant  store  of 
scientific  facts."  —  **  We  earnestly  recommend  to  scientific 
Agriculturists  and  to  Chemists  to  study  Liebig." 


'*By  the  perusal  of  such  works  as  this,  the  farmer  need  no 
longer  be  groping  in  the  dark,  and  liable  to  mistakes  ;  nor 
would  the  not  unnatural  odium  of  farming  by  the  book,  be 
longer  existent. 

**  In  conclusion,  we  recommend  the  work  to  the  Agricul- 
turist and  to  the  Horticulturist,  to  the  amateur  florist,  and  to 
the  curious  student  into  the  mysteries  of  organic  life,  —  as- 
sured that  they  will  find  matter  of  interest  and  of  profit  in 
their  several  tastes  and  pursuits." — Hovey's  Magazine  of 
Horticulture y  &c.,  September,  1841. 


''  We  regard  the  work  of  Liebig  as  a  work  of  extraordinary 
philosophical  acumen,  and  conferring  upon  him  the  highest 
honor.  The  more  it  is  examined,  the  deeper  will  be  the  inter- 
est which  it  will  create,  and  the  stronger  the  admiration  of  the 
ability  with  which  it  is  written.  It  is  not  a  work  to  be  read, 
but  studied  ;  and  if  further  inquiries  and  experiments  should 
demonstrate,  as  seems  to  us  from  many  facts  within  our  own 
knowledge  in  the  highest  degree  probable,  the  soundness  of 
his  views,  his  work,  not  merely  as  a  matter  of  the  most  inter- 
esting philosophical  inquiry,  but  of  the  highest  practical  utili- 
ty, will  be  invaluable." — JVbW/i  American  Review,  July,  1841. 


*'  Dr.  Webster  has  rendered  an  important  service  to  the  agricul- 
tural community,  by  presentinsr  an  edition  of  this  now  well  known 
and  highly  esteemed  work.  Professor  Liebig  has  for  some  time 
been  known  as  one  of  the  most  eminent  chemists  of  Europe,  and  the 
publication  of  this  work  in  England  has  excited  general  and  unqual- 
ified approbation.  Almost  all  the  scientific  and  literary  periodicals 
have  been  loud  in  its  praise,  and  all  concur  in  the  opinion,  that  a 
new  era  in  agriculture  must  date  from  its  appearance.  The  present 
edition  has  been  greatly  increased  in  value  and  utility  by  the  addi- 
tions which  it  has  received  from  the  American  editor.  The  Notes 
and  Appendix  contain  much  important  information  for  the  agricul- 
turist, and  the  explanations  which  have  been  added  of  chemical 
terms,  render  it  intelligible  to  all.  It  should  be  in  the  hands  of  every 
farmer.  The  typography  and  general  appearance  of  the  volume  is 
such  as  might  be  expected  from  the  University  Press."  —  Christian 
Examiner,  July,  184 J. 


*'  In  the  present  work,  Dr.  L.  has  pointed  out  the  path  to 
be  pursued,  and  has  amply  vindicated  the  claim  of  science  to 
be  considered  the  best  guide,  by  correcting  the  erroneous 
views  hitherto  prevailing,  of  the  sources  whence  plants  derive 
their  nourishment,  by  developing  the  true  causes  of  fertility 
in  soils,  and  finally,  by  establishing,  on  a  firm  basis,  the  true 
doctrine  of  manures." —  Quarterly  Revieiu,  March,  1842. 


NOTICE  OF  PART  II. 
ANIMAL   CHEMISTRY. 

"  While  we  have  given  but  a  very  imperfect  sketch  of  this  origi- 
nal and  profound  work,  we  have  endeavored  to  convey  to  the  read- 
er some  notion  of  the  rich  store  of  interesting  matter  which  it  con- 
tains. The  chemist,  the  physiologist,  the  medical  man,  and  the 
agriculturist,  will  all  find  in  this  volume  many  new  ideas  and  many 
useful  practical  remarks.  It  is  the  first  specimen  of  what  modern 
organic  chemistry  is  capable  of  doing  for  physiology;  and  we  have 
no  doubt  that,  from  its  appearance,  physiology  will  date  a  new  era 
in  her  advance.  We  have  reason  to  know  that  the  work,  when  in 
progress,  at  all  events  the  more  important  parts  of  it,  were  submit- 
ted to  Mailer  of  Berlin,  Tiedemann  of  Heidelberg,  and  Wagner  of 
Gottingen,  the  most  distinguished  physiologists  of  Germany ;  and 
without  inferring  that  these  gentlemen  are  in  any  way  pledged  to 
the  author's  opinions,  we  may  confidently  state  that  there  is  but  one 
feeling  among  them  as  to  the  vast  importance  of  Chemistry  to  Phys- 
iology at  the  present  period  ;  and  that  they  are  much  gratified  to 
see  the  subject  in  such  able  hands."  —  Quarterly  Revieiv, 


THE 

HISTORY  OF  HARVARD  UNIVERSITY. 

By  JOSIAH   QUINCY,  LL.  D., 

PRESIDENT    OF    THE    UNIVERSITY. 

CAMBRIDGE : 
PUBLISHED  BY  JOHN  OWEN. 

[Rojal  8vo.    Vols.  I.  and  II.    pp.  612  and  728.] 
21  Engravings. 


''  This  History  is  a  monument  of  patient  and  unwearied 
investigation,  —  of  rigid  impartiality  and  discrimination  in 
deductions  from  time-worn  records.  It  embraces  the  events 
of  two  centuries,  and  historical  and  biographical  notices  of 
nearly  every  individual  whose  name  is  found  connected  with 
any  important  incident  in  the  annals  of  the  University."  — 
Boston  Courier, 


''There  is  no  hazard  in  saying,  that  this  work  is  rich  in 
materials,  many  of  which  have  escaped  the  notice  of  even 
extensive  readers,  and  that  it  bears  marks  of  thorough  re- 
search, and  great  care  in  the  collection  and  verification  of 
facts,  and  judgment  and  skill  in  the  arrangement  and  devel- 
opement  of  the  narrative."  —  Daily  Advertiser. 


'•The  American  press  has  rarely,  if  ever  before,  sent 
forth  two  such  beautiful  volumes  in  typographical  execution, 
as  these,  containing  an  admirable  and  interesting  history  of 
the  venerable  University  of  Cambridge.  To  the  numerous 
Alumni  of  Harvard,  these  volumes  will  be  precious  indeed." 
—  JVeio  York  American. 

"  The  history  of  the  University  is  now  written  ;    and  it 
needs  no  prophetic  sagacity  or  boldness  to  assert,  that  it  will 


endure.  For  the  indefatigable  diligence  and  learned  re- 
search with  which  the  materials  have  been  assembled  ;  for 
the  fullness,  candor,  and  impartiality,  with  which  they  are 
now  exhibited  ;  for  the  light  reflected  thus  on  the  history, 
not  only  of  the  College,  but  of  the  times  ;  in  fine,  for  what 
he  has  here  done  to  establish  the  claims  of  Harvard  College, 
in  the  successive  periods  of  its  history,  to  the  gratitude  and 
veneration  of  her  sons  in  all  coming  time,. —  we  ofl?er  him, 
in  their  name,  nor  will  they  deem  it  presumptuous,  our  cor- 
dial thanks.*' —  Christian  Examiner, 


**  We  expected  to  find  in  these  volumes  the  authentic  re- 
sults of  diligent  research,  and  accordingly,  a  valuable  con- 
tribution to  the  completeness  of  existing  aids  to  an  acquaint- 
ance with  the  men  and  doings  of  the  ancient  times.  But  we 
confess  we  did  not  expect  to  find  them  so  fruitful  in  enter- 
tainment, and  in  materials  for  engaging  and  profitable,  as 
well  as  (to  a  patriot)  complacent  reflection.  We  did  not 
expect  to  see  a  record  of  the  fortunes  of  a  single  institution 
of  learning,  taking  the  place,  which  this  seems  to  us  des- 
tined to  take,  among  works  of  historical  literature. 

**This  is  not  a  book  to  be  welcomed  and  enjoyed  by  the 
friends  of  Harvard  College  alone,  nor  by  either  of  the  small 
classes  of  New  England,  or  of  academical  antiquaries,  but 
one  which  will  sustain  permanent  claims  on  the  attention  of 
the  general  student  of  history."  —  JYorth  American  Review. 


This  work  is,  in  fact,  not  simply  the  history  of  one  of  our 
most  ancient  literary  institutions,  but  a  history  of  the  prog- 
ress of  letters  in  New  England  from  the  earliest  days  of  the 
Puritan  colonists  ;  the  history  of  the  most  illustrious  minds, 
for  heroism  and  genius,  which  have  adorned  the  annals  of 
Massachusetts  for  the  last  two  centuries. 

The  whole  net  proceeds  of  the  sale  of  these  volumes  will 
be  devoted  to  assist  indigent  students. 


WORKS  RECENTLY  PUBLISHED  BY 

J.   OWEN,   CAMBRIDGE. 


THE  HISTORY  OF  HARVARD  UNIVERSITY,  by  Josiah 
QuiNCY,  LL.  D.,  President  of  the  University.  With  21  Engrav- 
ings.   2  vols,     royal  8vo.     cloth. 

VOICES  OF  THE  NIGHT,  by  Henry  Wadsworth  Long- 
fellow.   6th  edition.     16mo.     boards. 

THE   SAME,    royal  8vo.     fine  paper,     boards. 

THE  CLOUDS  OF  ARISTOPHANES.  With  Notes  by  C.  C. 
Felton,  Professor  of  Greek  Literature  in  Harvard  University. 
12mo.     cloth.  / 

LECTURES  ON  MODERN  HISTORY,  from  the  Irruption  of 
the  Northern  Nations  to  the  close  of  the  American  Revolution. 
By  William  Smyth,  Professor  of  Modern  History  in  the  Univer- 
sity of  Cambridge.  From  the  Second  London  Edition,  with  a 
Preface,  List  of  Books  on  American  History,  &c.,  by  Jared 
Sparks,  LL.  D.,  Professor  of  Ancient  and  Modern  History  in 
Harvard  University.     2  vols.     8vo.     cloth. 

BALLADS  AND  OTHER  POEMS,  by  Henry  Wadsworth 
Longfellow.     4th  edition.     16mo.     boards. 

THE  SAME,     royal  8vo.    fine  paper,     boards. 

A  NARRATIVE  OF  VOYAGES  and  Commercial  Enterprises, 
by  R.  J.  Cleveland.    2  vols.     12mo.     cloth. 

AN  INQUIRY  into  the  Foundation,  Evidences,  and  Truths  of 
Religion.  By  Henry  Ware,  D.  D.,  late  Hollis  Professor  of 
Divinity  in  Harvard  College.    2  vols.  12mo.    cloth. 

HENRY  OF  OFTERDINGEN :  A  Romance.  From  the  Ger- 
man of  Novalis  (Friedrich  von  Hardenberg).     12mo.    cloth. 


PROF.  LIEBIG'S  REPORT  ON  ORGANIC  CHEMISTRY. 

PART  I. 

AGRICULTURAL    CHEMISTRY. 

CHEMISTRY  in  its  Application  to  Agriculture  and  Physiology. 
By  Justus  Liebig,  M.  D.,  Ph.  D.,  F.  R.  S.,  M.  R.  L  A.,  Professor  of 
Chemistry  in  the  University  of  Giessen,  &c.  Edited  from  the 
Manuscript  of  the  Author,  by  Lyon  Playfair,  Ph.  D.  With 
numerous  Additions,  and  a  New  Chapter  on  Soils.  Third  Ameri- 
can from  the  Second  English  Edition,  with  Notes  and  Appendix, 
by  John  W.  Webster,  M.  D.,  Erving  Professor  of  Chemistry  in 
Harvard  University.    12mo. 


8 

PART  II. 

ANIMAL  CHEMISTRY. 

ANIMAL  CHEMISTRY,  or  Organic  Chemistry  in  its  Application 
to  Physiology  and  Pathology.  By  Justus  Liebig,  M.  D.,  Ph.  D., 
F.  R.  S.,  M.  R.  I.  A.,  Professor  of  Chemistry  in  the  University  of 
Giessen,  &c.  Edited  from  the  Author's  Mfinuscript,  by  William 
Gregory,  M.  D.,  F.R.  S.  E.,  M.  R.  L  A.,  Professor  of  Medicine 
and  Chemistry  in  the  University  and  King's  College,  Aberdeen. 
With  Additions,  Notes,  and  Corrections,  by  Dr.  Gregory,  and 
others  by  John  W.  Webster,  M.D.,  Erving  Professor  of  Chem- 
istry in  Harvard  University.     1  vol.  12mo. 


IN   PRESS, 

A  TREATISE  ON  MINERALOGY,  on  the  Basis  of  Thomson's 
Outlines,  with  Numerous  Additions ;  comprising  the  Description 
of  all  the  new  American  and  P^oreign  Minerals,  their  Localities, 
&c.  Designed  as  a  Text-Book  for  Students,  Travellers,  and 
Persons  attending  Lectures  on  the  Science.  By  J.  W.  Web- 
ster, M.  D.,  Professor  of  Chemistry  and  Mineralogy  in  Harvard 
University.    8vo. 

THE  EVIDENCES  OF  THE  GENUINENESS  OF  THE  GOS- 
PELS. By  Andrews  Norton.  Vols.  II.  and  III.  (being  the 
completion  of  the  work).    8vo. 


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